Below you can see the front-view size comparison of the Fujifilm X-E2S and Panasonic GX850. The Panasonic GX850 is clearly the smaller of the two cameras. Its body is 22 mm narrower, 10 mm shorter and 4 mm thinner than the Fujifilm X-E2S.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.