Ds had a ta/1:1 at nursery all the way through to now (high school). What they've done has changed as he has grown and changed. Mainstream nursery and primary and very specialised high school. I admit he should have moved before then. He had constant 1:1 at all times inc break and dinner (separate ta for these times) and 2:1 when off site/ school trips.
I'll list some of the things he's had help with over the years but the most important thing was personality and a willingness to try and think outside the box. Each child is different. I'd ask for the ehcp to read and any reports that go with that (if the ehcp is any good it should give you a lot of info on what you need to be doing and what the child needs to be done legally).
Personal hygiene needs/ helping with clothes etc
Cuddles and reassurance if needed, fun/laughter
Ot exercises (practical for motor skills and sensory)
Using communication aids both high and low tech/ other slt techniques etc
Making resources
Differentiating materials (this should be done by the teacher in reality)
Breaking tasks down for him
Emotional regulation
Getting trained with various skills they needed (equipment/ it)
Ensuring his safety
Getting any equipment out he needs/ packing it away
Helping him with friendships
Helping him physically, how to hold pens/ crayons, move, eat, drink
Making sure he understands whatever he needs to understand (different to the rest of the class).