If there are students like this in a class then there are some things the teacher can do.
There used to be a service that would advise on students with behavioural needs. It may have been cut but the school may be able to ask for that support from the LA if it still exists.
If not, then the advice more generally for the teacher would be to look for what is triggering that behaviour and trying to either avoid if possible or put something in place so that the behaviour doesn't happen.
A fairly obvious example is that many students with SEND find unstructured time difficult. So they might be allowed to come in 10 mins late to avoid the cloakroom maelstrom, etc. or the teacher might set up a group of friends for them to play with at play time.
Most of these are much easier to implement with a TA.
It sounds like the behaviour is sufficiently difficult that they have taken the decision not to allow the class to do PE because of the risk of physical injury.
You could ask that alternative arrangements be set up for PE - for example if there is more than one class in a year then a group of children from both classes do PE one week while the others do art, and then it switches but some students stay in the art class. This could be sold as they are specialising in art, or doing an intervention or whatever.
Keeping them in at break is generally considered bad practice but it does work to moderate behaviour which is why teachers use it.
Realistically if there are multiple students who are like this and there is no additional TA support from the school, the process to apply for additional money from the LA to support the needs of these children is long and time consuming.
In your shoes I would move school.