The theory that she's on the spectrum is pretty popular, esp since her brother is actually diagnosed. But honestly, I think it's impossible to tell based on her behavior now. Her brain is living in a starvation fog making her sound incredibly dumb, her ED is at an all time high, the anorexia idiosyncrasies present in her every gesture. Also, her developmental stunting can be explained by this as well: she's suffered from anorexia for 10+ years and this is an illness that is isolating, like most EDs (can't go out b/c people stare, you have to eat, you worry abt food being present, you're tired all the time and can't keep up). She has also cut off all of the people who confronted her abt it in anyway, to the point where she has no other friends now. The only notable difference between her and most other anorexics is that her family seems to be ignoring and even enabling her illness and the entire family in general seems very secluded (no vacations or outings of any kind, no hobbies, etc... I think Chip is probably the one with the most active social life and he's autistic and morbidly obese.. Like, damn).
But back to the idea of her being on the spectrum, I truly think that even a psychiatrist would need her to first work on her ED (gain some weight and improve eating habits) and only then they could maybe test her for autism.
Outside of this, if you look at her videos from when she was better and/or from years ago when she wasn't so into her ED, she acted normal, maybe a little awkward but that can just be teenage awkwardness. She seemed to have more interests and hobbies, was pretty sarcastic and more confident in expressing her feelings and standing up for herself, went out and socialized more, had an actual interest in creating content for YT, i.e. smth that can be considered a goal, etc.
Personally, I think her ED is more tied to some sort of trauma, maybe her parents separating or her brother being the center of attention when they were young due to his autism, combined with the bullying and body insecurities she developed (clearly re: her face and height) that were maybe exacerbated in her teenage years when she was pursuing modeling (people in this business have no problem telling kids you're too fat, lose weight, you're too tall/short, your face is too wide, you need to turn to the side, etc etc).