As PPs have said - there is no 'normal'. Don't spend more than you can afford must be the only rule. As you mentioned, we stop buying basics in the run up to Christmas so the children get socks, pants, school socks, bubble bath etc in their stockings, along with sweets and maybe some small games or toys. Nothing worth more than a fiver - anything else is a 'proper present'.
My two haven't asked for anything much this year - last year was a Nintendo Switch between them, so I made them do chores and use savings to put £100 towards it, and we bought the rest. Plus clothes (I have bought mine several charity shop items this year, we aren't poor, I just hate waste and they grow so fast....).
This year I also got some boots for DS that I know he needs, and several items around the £10/20 mark that they'd asked for. I got some second hand from ebay. Aunts and Uncles spend £10 per child, and we have lovely godparents who spend a bit more! We got my DD a second hand phone from ebay for £90 which she hadn't asked for, but she's at secondary school and all her friends have them. I'm getting a £10 PAYG SIM for it.
It probably does come to about £200 each from us. We are lucky to be able to spend that but we never buy rubbish and always try to get good value. Both have asked for socks, pants and mostly sweets on their lists, so they aren't grabby. But we all love coming down in the morning and seeing huge piles of stuff to unwrap - it's so magical!! OP - yours are a lovely age, enjoy!