Because of course she can do that.
I wasn't sure about addressing Rhoda's ability to mess with figure proportions in general just yet, but a lot of people have been wondering about this (SHOCKING, I know), and I thought this a fun way to confirm and show that Rhoda has even more up her sleeve, so here we go.
Incidentally, Rhoda is in "tall mode" in that third panel in part just to demonstrate that these particular enchantments do not cancel each other out and can be stacked.
...I swear I wrote "can be stacked" without any intent of pun and only just realized what I'd done a moment later.