That's interesting. To test it out, I went to Settings/Mouse/Theme/Size, and changed it from 16 to 24. Weirdly, the mouse stayed the same size, but the fonts of everything else got smaller. So, arguably, relative to everything else, the mouse is larger. But this is not what should be happening. Obviously the mouse should grow rather than everything else shrink. It almost seems like a practical joke that some coder put in.
Hopefully when I restart this computer, the fonts will return to where they were previously (which didn't happen when I tried to reset it back to 16.) I'm using VL-7.0 on XFCE.
Anyway, good luck with finding out how to resize the cursor. Alas, I don't have the answer.