That premise reminds me of the short story “Too Tall”, where the protagonist is a gymnast who had a recent growth spurt that made her too tall and gangly to be much good any more, and when a snug, petite rival low-key rubs the protagonist girl’s face in still being awesome, protagonist girl wishes the rival was too tall instead.
So as the rival steps up to compete, every category of her routine, she grows taller and curvier, until her leotard explodes off her and she stands taller than the uneven bars, which I think are like 8ft or 9ft tall. Feeling guilty as the rival gets laughed at for breaking the uneven bars just trying to lift herself, deeply confused at what’s happening, the protagonist girl leads them both outside for a talk, but that’s where it sadly ends.
I always wished there was a follow up where the protagonist reveals she thinks it was her fault the rival grew, and the rival wishes back that the protagonist knew how it felt to grow into a public spectacle, and thus have the protagonist then grow even bigger and curvier than the rival. Whether that would be it or the story devolves into a king-size canary style growth wish back-and-forth, or the newly giantess protagonist takes the loss is stride, who knows.