@Comfysofa78 When my DD was out of school and did not want to engage with the world, I found local home ed groups with meet ups, where we found the children had a very friendly and welcoming attitude and would take dd off to play.
Also, meeting up 1:1 with a few particular friends.
Small steps - showed her how her expectations and the reality were very far apart: that she was not 'weird' and got on with anybody and everybody, was a kind and fun friend. Self- esteem building.
Again, making lists.
We would do things such as:
Words to describe myself and my personality.
What makes me happy?
Who makes me happy? How?
What makes me sad?
Who makes me sad? Why?
She found that her negative attributes (we all have them) list was much smaller than her positive qualities.
What she enjoyed much more than a small number of things that upset her.
More people and children that she got on with well than didn't.
We did this a few times over 4months, which got her started and in a good place to even think about going back to school; then school visit, tentative positivity, then bumpy reality for a couple of terms with a small level of refusal and fear - deep breathing, comics, blowing soap bubbles on way to school. A positive experience would be a small powerful building block to help build confidence back.
Also, with lists - what did she want for her future? How could we work towards getting there?
It's a lot of things - identifying triggers and physical response, rationalising, distraction, coping, facing up to! (the hardest but most powerful tool), talking things through, relaxation, fun, good sleep (we employed audio books at bedtime to avoid fretting at night), walks and fresh air.
Clearly, this was pre-pandemic for us.