Below you can see the front view size comparison of Panasonic GH5S and Nikon D500. Panasonic GH5S is 8mm narrower and 17mm shorter than Nikon D500 but it is also 6mm thicker.
Panasonic GH5S vs Nikon D500 - Front View
Panasonic GH5S vs Nikon D500 - Top View
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.
Camera Size Comparison
Select Two Cameras for Size Comparison