Below you can see the front view size comparison of Nikon D850 and Fujifilm GFX 50R. Fujifilm GFX 50R is 27mm shorter and 13mm thinner than Nikon D850 but it is also 15mm wider.
Nikon D850 vs Fujifilm GFX 50R - Front View
Nikon D850 vs Fujifilm GFX 50R - 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