Below you can see the front view size comparison of Canon 1D X II and Sony A9. Sony A9 is clearly the smaller of the two cameras. Its body is 31mm narrower, 72mm shorter and 20mm thinner than Canon 1D X II.
Canon 1D X II vs Sony A9 - Front View
Canon 1D X II vs Sony A9 - 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