Below you can see the front-view size comparison of the Fujifilm X-A3 and Nikon 1 V3. The Nikon 1 V3 is clearly the smaller of the two cameras. Its body is 6 mm narrower, 2 mm shorter and 7 mm thinner than the Fujifilm X-A3.
The chart below depicts how two cameras compare with average dimensions of the cameras in their class.