Below you can see the front-view size comparison of the Olympus E-M10 II and Pentax K-S2. The Olympus E-M10 II is clearly the smaller of the two cameras. Its body is 3mm narrower, 8 mm shorter and 26 mm thinner than the Pentax K-S2.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.