There you go again. As it stands, the girl in this topic is exactly that. A girl. She might want to identify as a boy, but she is, at the moment, a girl.
When she gets older, she may feel the same, or even feel stronger that she’s a man trapped in a woman’s body. She can then put the wheels in motion to surgically become a man.
Only then, can she claim to be a man.
A lot of kids at that age are confused, mixed up and emotionally unstable.