I alluded to this before, but people with gigantism can temporarily gain massive muscle mass and bone strength by simply working out for an extended period of time and keep on that bulk as long as they regularly exercise.
The outreach program Eclair joined also has a gym training program called "Gym Belles" where young girls like her can go work out together and train their muscles if they so wish. Although Eclair doesn't do it as often, when she feels like pumping up, she really can pump up! Although she doesn't tend to stay this big for while since she doesn't train as intensely as other people, but it is a good way to meet other girls her age like her, some I might introduce in the future.
Though if you think she is big now at this age, just wait until she bulks up as an adult! Might do that some day as well.
Anyways, hope you all enjoy!