Below you can see the front view size comparison of Sony RX10 IV and Nikon Z6. Sony RX10 IV is 1mm narrower and 7mm shorter than Nikon Z6 but it is also 77mm thicker.
Sony RX10 IV vs Nikon Z6 - Front View
Sony RX10 IV vs Nikon Z6 - 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