Below you can see the front-view size comparison of the Pentax K-1 and Olympus E-M1 II. The Olympus E-M1 II is clearly the smaller of the two cameras. Its body is 3 mm narrower, 19 mm shorter and 19 mm thinner than the Pentax K-1.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.