@Soontobe60
I think you’ve hit the nail on the head - the dd needs to have the internet access surgically removed and some good firm discipline. Screaming at adults, attacking other children? I’m amazed she’s not been suspended from school.
Noticeable that she/they/pronouns of choice physically assaulted the child with SEN, isn't it? Bet he was the one least likely to thump her one in self defence from the nasty, scratchy, stereotypical girl attack. Didn't attack the elderly man where there would be witnesses
and a criminal record for assault either, just throwing histrionics
also a stereotypical girl response.
Groups of kids can get into spirals of negative behaviour - eating issues, self harm, disruption, shoplifting, drinking, violence, anything you don't want kids to do, there will be a small friendship group that can end up continually raising the stakes to be the loudest, toughest, most unwell, thinnest, most needy, most controlling, stupidest... Your DD is not responsible for their wellbeing, is not required to agree with anything they say, does not have to go along with any of it and certainly should be supported to recognise toxic group and relationship dynamics and extricate herself from them without needing to say anything that could be interpreted as transphobia or being mean about them. They're just not as much fun anymore and attacking people could well be the limit, especially as she doesn't want to find herself sat in the police station waiting for you to get there because the others have attacked another easy target person who has unwittingly fallen foul of how they wish to be perceived.
They aren't the only five people in the year your DD can be friends with. It's very normal as kids get older to find different friends. And as she's at the end of her tether with them, some support in that, especially when they're back in school from her Head of Year, for example, could be just what she needs to join or form another group of friends with a healthier dynamic.