Below you can see the front-view size comparison of the Fujifilm X-Pro2 and Fujifilm X-E3. The Fujifilm X-E3 is clearly the smaller of the two cameras. Its body is 20 mm narrower, 9 mm shorter and 13 mm thinner than the Fujifilm X-Pro2.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.