Below you can see the front view size comparison of Sony A6300 and Sigma Quattro H. Sony A6300 is clearly the smaller of the two cameras. Its body is 27mm narrower, 28mm shorter and 42mm thinner than Sigma Quattro H.
Sony A6300 vs Sigma Quattro H - Front View
Sony A6300 vs Sigma Quattro H - 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