Not sure what the Genesis of the condition would be. If you have a story where there is an inventor who creates mind control, imagine he also creates a growth serum. It could just be random genetics.
Here's the setup: very attractive popular girl starts growing at a rapid rate. She quickly outgrows any clothes she has , in fact they don't make them in her size anymore.
So, you have almost the naked in school recipe here.
She might be able to wrap some towels around her but enormous tits, pussy and ass will eventually pop out if she continues to grow.
When she reaches 20 ft or more tall, she may have to give up on finding clothes/covering her body.
It isn't just about her adjusting to her new life. It's about her clinging to her old one. How does she have sex with her boyfriend? HIs entire fist may not satisfy her.
Maybe she starts getting strange cravings for sex. Maybe the guy who gave her the growth serum tells her he can reverse it but she has to subject herself to his strange sexualy chwrged experiments.
"I'm going to connect this battery cable to your nipples, Amanda"
" Wait how is that gonna help m..
Aaahhhhhhhh"
" Interesting let's try it again"
You could explore how her family reacts to the giantess in their home and when she outgrows being able to get through the door, living in the backyard. Maybe she starts standing up for her little brother when he gets bullied. Maybe dad uses her almost like a crane to help him finally fix the roof. The family finds ways to deal with and accept her condition.
Could you do anything with a story like that?