I would first off reduce any pressure or expectations from home. Secondly approach school - teacher and head, highlight how stressed your dc is and open a dialogue. Think about what will help her approach them more positively, she may well be doing exams just a few months later in secondary. If your older dc didn't do SATs due to covid then none of their peer group will have so they will presumably be setting, calculating flight paths, progress8 etc differently for that whole year group. Don't assume that it will be the same for your current child. As the secondary school and other parents what impact SATs have.
All secondary schools are different. One secondary school my dc were at didn't set at all, the other one used internal tests and SATs to stream off a top set for some subjects. Those without SATs results or low SATs results were less likely to be in the top stream. The SATs also influenced interventions for GCSEs. No additional support, invites for revision sessions were given to those who were on track or exceeding, however low their flight path. These were strongly pushed for those who had dropped below their expectations based on SATs. Essentially you could have a child in yr 11 on track for a 4 in physics, but because their predictions were a 3 they got no additional sessions whereas someone on track for a 6 would get sessions because they should have been getting an 8, they were also placed under a lot of scrutiny for why they weren't doing well, but not necessarily in a good way.
I can understand from a school perspective, it was a large, aspirational school with limited resources and a close eye on league tables, the reason it was popular. It didn't necessarily mean they achieved the best they could have done for their current pupils in terms or results or in terms of mental health support.
You may though not be too concerned about how well your child does at GCSEs. I don't mean that in a negative way. I think the current emphasis on predominantly academic subjects until 16 is off putting to many children. They would be much better on a more practical curriculum and planning towards a trade, which might be more immune in the short term to AI anyway. They can do a degree later in life if they want to. If your child is like that then perhaps the whole of secondary to GCSE will be about containing their anxiety until they can branch off into a subject that they feel passionate about.