Below you can see the front view size comparison of Fujifilm X-T3 and Pentax K-1 II. Fujifilm X-T3 is clearly the smaller of the two cameras. Its body is 4mm narrower, 17mm shorter and 27mm thinner than Pentax K-1 II.
Fujifilm X-T3 vs Pentax K-1 II - Front View
Fujifilm X-T3 vs Pentax K-1 II - 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