It really depends on how much overlap you use in my experience. With 1 layer of full 50% overlap using g09 grips, the grip seems to be slightly thicker than original grip.
Stretching and how much u overlap makes a huge difference. I put a heavily stretched no overlap on top of original grip, then top layer half stretched, half overlap. This is on a G5 handle. Think it makes it comparable to a G3-G4 with 1 overgrip. I used to put similar but on wood if its a g3. Not sure why these days all rackets are g4 and g5 which I find too small (I dont have big hands either).