I just looked it up. It's 48 x 48 by default
I think they look amazing! I like them just not the right size. :(
You can resize them by x3. 16 * 3 = 48.
Turn off resize filters to keep the pixels looking good (off is sometimes called nearest-neighbor and other names).
Besides resizing the tiles you will need to arrange them into RPG Maker MV tile maps (some of which are auto-tile maps).