Below you can see the front-view size comparison of the Fujifilm X-A5 and Pentax K-S2. The Fujifilm X-A5 is clearly the smaller of the two cameras. Its body is 6mm narrower, 23 mm shorter and 33 mm thinner than the Pentax K-S2.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.