I just found another question on the physics exchange asking the exact same thing here. Apparently the European Space Agency did some research on that and found that even simply emerging in water with air breathing can go up to 24g. With liquid breathing they just wrote that the limits are hard to estimate and probably hundreds of g are possible. They also wrote that in clinical lung therapy method for liquid breathing already exist using a liquid called perfluorocarbon.

I just found another question on the physics exchange asking the exact same thing here. Apparently the European Space Agency did some research on that and found that even simply emerging in water with air breathing can go up to 24g. With liquid breathing they just wrote that the limits are hard to estimate and probably hundreds of g are possible. They also wrote that in clinical lung therapy method for liquid breathing already exist using a liquid called perfluorocarbon.

Edit: An example what this could mean for a fictional story. Suppose you accelerate at a rate of 100g, or 1000m/s^2. This means starting from zero you will reach Earth escape velocity after around 11 seconds (you probably shouldn't do that on Earth inside the athmosphere), solar escape velocity after around 10 minutes and 25% of the speed of light after 24 hours of constant acceleration. Plenty enough for interstellar travel in a hard science setting.