Wellllllll.... She's got a fairly wide chest/shoulders and a longish torso compared to the rest of her frame, and she also can't stand anything feeling "tight" near her underarms.
So yes, it often means sizing up a little sooner than maybe the average kid might. That said, she's seriously outgrown all CL GK/UA workout leotards - she could maybe squeeze into 1 or 2 yet, but doesn't.
Her comp leo is a GK CL, and it has a little bit of give yet, but we find comp leos to run larger than the in-stock tanks (and no tank strap to bug her underarms...).
She's got room to grow in her AXS leos, but it definitely seems to be her 'size' these days. Except we've been buying AS in Plum.
I'd definitely suggest trying an AS or AM in Plum. It seems to be pretty universal that they run about a size or so smaller than GK.