Below you can see the front-view size comparison of the Fujifilm X-A3 and Fujifilm JX370. The Fujifilm JX370 is clearly the smaller of the two cameras. Its body is 22 mm narrower, 10 mm shorter and 16 mm thinner than the Fujifilm X-A3.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.