In every school, there will be children that are not very nice and I do wonder whether this is just something she’s not going to be able to cope with, especially as kids get older and social rules get more complex.
I don't know whether this will be of any reassurance to you, but I believe that the vast majority of this not-nice behaviour is the result of schoolchildren spending so much time in an environment which is at least slightly stressful and unnatural for all of them. The school social setting is different from almost anywhere else, and has its particular challenges.
For example, during the school day, schoolchildren don't have easy access to adults who know them well, love them, and have time to help them. They are closely controlled and have little choice in how to spend their time, or with whom. For many hours every weekday they are with exactly the same set of kids. There is crowding and overstimulation. While many NT children can cope with that, it does take its toll. Sometimes they take it out on other people, or just go into survival mode, lacking the energy to be kind and helpful.
If you tune in to kids' behaviour in settings other than school, I think you'll notice they tend to be kinder. Relentless bullying is possible but rare in sports clubs, drama groups, neighbourhood playing, and home education groups. I think there are a lot of reasons for this. They are under less stress. They've chosen to be there, and presumably enjoy what they're doing. The adults around them are in a position to intervene, and even kick out troublemakers. Parents may be on hand. Even if kids are treated badly, ultimately they have the option of leaving, choosing a different football team or swim lesson.
Most adults aren't deliberately unkind to each other. We tolerate and sometimes even celebrate quirkiness. So in the very long run, your daughter doesn't have to conform completely to complex social rules in order to survive. In the short run, she'll often be fine outside of school, though maybe not at school.
My younger daughter, who's 19, doesn't have autism. She does have a learning disability and has never been like other kids. I can count on the fingers of one hand the times someone has been really unpleasant to her over it. I'm sure that's linked to the fact she has never been to school. She has many friends of all ages and abilities who like her for who she is. There are others who feel that she isn't really their cup of tea, but they politely do their own thing and aren't hurtful about it. Socially, home education has been the making of her. Nobody has ever given her the idea that there is something wrong with her. She's happy and confident.