My dd struggled a bit years 7 and 8 but then fell into a big group in year 9. She's quiet, studious, loves reading, struggled to connect. Was bullied a bit in primary.
Her social skills got better, that helped. Eye contact, smiling, initiating conversation.
We got Disney Plus, Netflix, Spotify and various computer games.
They seem to connect by liking the same programmes, music, computer games mainly, then playing them as a group, or watching a boxset.
I think they need something to latch onto. As they get setted in year 9 they meet more people. If they can find a shared like, it's the start of something.
I also think encouraging dd to think a little about fashion helped. She wasn't too into it previously but it helps with fitting in.
I worried terribly about dd but honestly by mid year 9 she was out every weekend doing something or other.. Dh has become the taxi driver. They just need one or two to let them in.