Below you can see the front view size comparison of Canon 77D and Canon T6s. Canon 77D is clearly the smaller of the two cameras. Its body is 1mm narrower, 1mm shorter and 2mm thinner than Canon T6s.
Canon 77D vs Canon T6s - Front View
Canon 77D vs Canon T6s - 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