I'm a parent of an autistic girl who now says she's a boy.
I really wish her teachers hadn't fallen over themselves to show how accepting they were of her new identity. It actually seemed like they were delighted to be able to prove how great they were at equality.
What she actually needed and still needs is affirmation that it's perfectly ok not to be a stereotypical girl (most of us actually aren't) and that what she thinks is gender is actually personality. She doesn't need to reinvent herself because she doesn't fit the girly girl image.
All we can do as parents and her family is to keep reinforcing how great she is just as herself while it seems other people, particularly some teachers, seem to have lost touch with common sense. It would have been ok to say no to her pronouns and new name and to tell her these are decisions for when you are older and have more life experiences.
She's 13 with a maturity age of around 10. We would also have said no to tattoos and body piercings had she decided that was going to be her thing. We have also said no to dying her hair blue unless in the school holidays.
Teens experiment with who they are. They always have done through things like being a goth, a punk, a mod etc. Never before though have so many, seemingly previously sensible adults, also jumped on the same bandwagon, to be part of the teen phase. That's where things have gone very wrong.