The purpose of the gospel of "John" is given here:
[Jhn 20:30-31 NASB95] [30] Therefore many other signs Jesus also performed in the presence of the disciples, which are not written in this book; [31] but these have been written so that you may believe that Jesus is the Christ, the Son of God; and that believing you may have life in His name.
The narratives occur to fulfil what was written:
[Jhn 15:25 NET] [25] Now this happened to fulfill the word that is written in their law, 'They hated me without reason.'
Luke also asserts that Christ's mandate is to fulfil all that is written:
[Luk 21:22 NET] [22] because these are days of vengeance, to fulfill all that is written.
[Luk 22:37 NET] [37] For I tell you that this scripture must be fulfilled in me, 'And he was counted with the transgressors.' For what is written about me is being fulfilled."
[Luk 24:44 NET] [44] Then he said to them, "These are my words that I spoke to you while I was still with you, that everything written about me in the law of Moses and the prophets and the psalms must be fulfilled."
Matthew also makes it plain that he knows what his job is:
[Mat 1:22 NKJV] [22] So all this was done that it might be fulfilled which was spoken by the Lord through the prophet, saying:
[Mat 2:15, 23 NKJV] [15] and was there until the death of Herod, that it might be fulfilled which was spoken by the Lord through the prophet, saying, "Out of Egypt I called My Son." ... [23] And he came and dwelt in a city called Nazareth, that it might be fulfilled which was spoken by the prophets, "He shall be called a Nazarene."
[Mat 4:14 NKJV] [14] that it might be fulfilled which was spoken by Isaiah the prophet, saying:
[Mat 8:17 NKJV] [17] that it might be fulfilled which was spoken by Isaiah the prophet, saying: "He Himself took our infirmities And bore [our] sicknesses."
[Mat 12:17 NKJV] [17] that it might be fulfilled which was spoken by Isaiah the prophet, saying:
[Mat 13:35 NKJV] [35] that it might be fulfilled which was spoken by the prophet, saying: "I will open My mouth in parables; I will utter things kept secret from the foundation of the world."
[Mat 21:4 NKJV] [4] All this was done that it might be fulfilled which was spoken by the prophet, saying:
[Mat 26:56 NKJV] [56] "But all this was done that the Scriptures of the prophets might be fulfilled." Then all the disciples forsook Him and fled.
[Mat 27:35 NKJV] [35] Then they crucified Him, and divided His garments, casting lots, that it might be fulfilled which was spoken by the prophet: "They divided My garments among them, And for My clothing they cast lots."
Note that references to Jesus "fulfilling the Law and the Prophets" are not about Jesus obeying the Law so that we don't have to or that because the Law was "obeyed perfectly" that is immediately self-destructs; that's not how law works!
Nor is about predictions occurring. The Law and the Prophets contain stories about Israel and the Jews and are all Jewish history. The NT authors strive to show that all of the history of the Jews was repeated in the life and times of Jesus, the LORD's Anointed Son of David.
A careful reading of the gospels betrays the hand of man in "fulfilling" these tropes. For example, Matthew read this prophecy and pondered how to fulfil it:
[Jdg 13:2-7 NASB95] [2] There was a certain man of Zorah, of the family of the Danites, whose name was Manoah; and his wife was barren and had borne no [children.] [3] Then the angel of the LORD appeared to the woman and said to her, "Behold now, you are barren and have borne no [children,] but you shall conceive and give birth to a son. [4] "Now therefore, be careful not to drink wine or strong drink, nor eat any unclean thing. [5] "For behold, you shall conceive and give birth to a son, and no razor shall come upon his head, for the boy shall be a Nazirite to God from the womb; and he shall begin to deliver Israel from the hands of the Philistines." [6] Then the woman came and told her husband, saying, "A man of God came to me and his appearance was like the appearance of the angel of God, very awesome. And I did not ask him where he [came] from, nor did he tell me his name. [7] "But he said to me, 'Behold, you shall conceive and give birth to a son, and now you shall not drink wine or strong drink nor eat any unclean thing, for the boy shall be a Nazirite to God from the womb to the day of his death.'"
Now, a Nazirite is somebody that takes a vow to abstain from Tequila and to gift all of their hair to God. The prophecy was about Samson:
[Jdg 16:15-20 NASB95] [15] Then she said to him, "How can you say, 'I love you,' when your heart is not with me? You have deceived me these three times and have not told me where your great strength is." [16] It came about when she pressed him daily with her words and urged him, that his soul was annoyed to death. [17] So he told her all [that was] in his heart and said to her, "A razor has never come on my head, for I have been a Nazirite to God from my mother's womb. If I am shaved, then my strength will leave me and I will become weak and be like any [other] man." [18] When Delilah saw that he had told her all [that was] in his heart, she sent and called the lords of the Philistines, saying, "Come up once more, for he has told me all [that is] in his heart." Then the lords of the Philistines came up to her and brought the money in their hands. [19] She made him sleep on her knees, and called for a man and had him shave off the seven locks of his hair. Then she began to afflict him, and his strength left him. [20] She said, "The Philistines are upon you, Samson!" And he awoke from his sleep and said, "I will go out as at other times and shake myself free." But he did not know that the LORD had departed from him.
However, Matthew understood his mandate was for all of the Law and the Prophets be about the Jesus event, and if he fails, the whole Jesus mythology fails. So he creatively (and some might say, disingenuously) by having Jesus miraculously moved to a town called Nazareth!:
[Mat 2:19-23 NET] [19] After Herod had died, an angel of the Lord appeared in a dream to Joseph in Egypt [20] saying, "Get up, take the child and his mother, and go to the land of Israel, for those who were seeking the child's life are dead." [21] So he got up and took the child and his mother and returned to the land of Israel. [22] But when he heard that Archelaus was reigning over Judea in place of his father Herod, he was afraid to go there. After being warned in a dream, he went to the regions of Galilee. [23] He came to a town called Nazareth and lived there. Then what had been spoken by the prophets was fulfilled, that Jesus would be called a Nazarene.
Notice how Matthew makes his move to Nazareth a miraculous intervention. Luke follows suit, however, in his "fulfillment" of Samson's Nazarite thing, Jesus' family was from Nazareth all along and only went to Bethlehem for some bogus Roman taxation fiasco:
[Luk 2:4, 39 NASB95] [4] Joseph also went up from Galilee, from the city of Nazareth, to Judea, to the city of David which is called Bethlehem, because he was of the house and family of David, ... [39] When they had performed everything according to the Law of the Lord, they returned to Galilee, to their own city of Nazareth.
The point is, these are not reliable eye-witness accounts but rather lie-witness accounts, because they don't agree.
So if Jesus did not actually fulfil "he shall be a Nazirite," and flat out disagrees with Luke, who said this:
[Luk 1:1-4 NET] [1] Now many have undertaken to compile an account of the things that have been fulfilled among us, [2] like the accounts passed on to us by those who were eyewitnesses and servants of the word from the beginning. [3] So it seemed good to me as well, because I have followed all things carefully from the beginning, to write an orderly account for you, most excellent Theophilus, [4] so that you may know for certain the things you were taught.
So is Luke right? Is Matthew? Once you realize how contrived these stories really are you can appreciate them for what they are: mythology, legends and metaphor.
So what did Matthew intend to "prove" by his added claim about the risen corpses? I speculate that it was intended to "fulfil" this:
[2Ki 13:21 NET] [21] One day some men were burying a man when they spotted a raiding party. So they threw the dead man into Elisha's tomb. When the body touched Elisha's bones, the dead man came to life and stood on his feet.
It's a bit incongruent but I do think that Matthew was referencing that story. I might also speculate that "after the resurrection" was added to Matthew later.
On the other hand, I speculate that Luke changed Matthew's account and has this story in mind:
[Jos 20:6 NKJV] [6] 'And he shall dwell in that city until he stands before the congregation for judgment, [and] until the death of the one who is high priest in those days. Then the slayer may return and come to his own city and his own house, to the city from which he fled.' "
We should note also that Matthew's gospel adds another angel and another miracle a little further on:
[Mat 28:1-10 NKJV] [1] Now after the Sabbath, as the first [day] of the week began to dawn, Mary Magdalene and the other Mary came to see the tomb. [2] And behold, there was a great earthquake; for an angel of the Lord descended from heaven, and came and rolled back the stone from the door, and sat on it. [3] His countenance was like lightning, and his clothing as white as snow. [4] And the guards shook for fear of him, and became like dead [men]. [5] But the angel answered and said to the women, "Do not be afraid, for I know that you seek Jesus who was crucified. [6] "He is not here; for He is risen, as He said. Come, see the place where the Lord lay. [7] "And go quickly and tell His disciples that He is risen from the dead, and indeed He is going before you into Galilee; there you will see Him. Behold, I have told you." [8] So they went out quickly from the tomb with fear and great joy, and ran to bring His disciples word. [9] And as they went to tell His disciples, behold, Jesus met them, saying, "Rejoice!" So they came and held Him by the feet and worshiped Him. [10] Then Jesus said to them, "Do not be afraid. Go [and] tell My brethren to go to Galilee, and there they will see Me."
That is so contradictory to the other gospels:
[Jhn 20:1-10 NKJV] [1] Now on the first [day] of the week Mary Magdalene went to the tomb early, while it was still dark, and saw [that] the stone had been taken away from the tomb. [2] Then she ran and came to Simon Peter, and to the other disciple, whom Jesus loved, and said to them, "They have taken away the Lord out of the tomb, and we do not know where they have laid Him." [3] Peter therefore went out, and the other disciple, and were going to the tomb. [4] So they both ran together, and the other disciple outran Peter and came to the tomb first. [5] And he, stooping down and looking in, saw the linen cloths lying [there]; yet he did not go in. [6] Then Simon Peter came, following him, and went into the tomb; and he saw the linen cloths lying [there], [7] and the handkerchief that had been around His head, not lying with the linen cloths, but folded together in a place by itself. [8] Then the other disciple, who came to the tomb first, went in also; and he saw and believed. [9] For as yet they did not know the Scripture, that He must rise again from the dead. [10] Then the disciples went away again to their own homes.
I mean, they are completely different! They cannot both be true. And since Matthew does not have a second witness, we can be sure that at least Matthew would not stand up in a court of law.
Addendum
I looked at what the Hebrew Gospel of Matthew, and this is what it has:
Matthew 27:
50 Jesus cried another time in a loud voice and sent his spirit to his father.
51 Immediately the curtain of the temple was tom into two pieces, from the
top downwards; the earth shook and the rocks were broken.
52 The graves were opened and many of those asleep in the dust arose.
53 They came out of their graves and after (this) they entered the holy city and were revealed to many.
54 The captain of the hundred and those standing with him watching Jesus
saw the earthquake and the things which were done and were very afraid
saying: Truly this was the Son of God.
If, as is likely the case, the 65 manuscripts found some 25 years about represent an ancient witness, then indeed "after his resurrection" is a textual corruption.