Below you can see the front view size comparison of Nikon D850 and Nikon D5600. Nikon D5600 is clearly the smaller of the two cameras. Its body is 22mm narrower, 27mm shorter and 9mm thinner than Nikon D850.
Nikon D850 vs Nikon D5600 - Front View
Nikon D850 vs Nikon D5600 - 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