Well, that would depend on what’s in the other 3D “layers” of the 4D world. Like how 3D worlds can be thought of as layers of 2D ones. If you moved to another 3D “layer” that had no oxygen, food, water, etc., you would quickly die. If you moved quick enough you would also probably die, but the same could be said about the three spatial dimensions we’re used to. Also, if there was a fourth spatial dimension, it must be “squished” enough that we can’t detect it with our current technology, and I have a hunch (!!! no evidence for this, please search for some if you want good facts!!!) it would be bad for us to move through it.