I too have a 4yr old that. Does. Not. Stop. Ever. It's exhausting!! Different situation as SEN and language delay but I just wanted to say I feel you. Thankfully my other child is older as I'm not sure how I'd cope if I had a younger child, I mean I would because I'm a mam and we just do don't we.
No solutions, I've given up and just lean into the crazy now lol tbh he's actually a lot of fun he's cute, cheeky, funny and gets me to the point where I'm gonna do time and then flips it round by doing something to melt me 🙄 I've accepted I live in a shit hole by day and a Palace by night, albeit a Palace that's tidy but with ripped wallpaper on every wall, broken toys and knackering to set straight every night (shhh don't tell but sometimes I don't tidy every night!)
We bounce on the bed, run races, have dance parties, just anything energetic he wants to do for those few hours between home from school and bedtime. He has a tall stairgate on his bedroom door (because of his SEN and before anyone comes at me we have a disability SW and they approve) so he has a safe place to be put for 5 mins if i desperately need a time out (with toys in his "prison" again before anyone comes at me) Thankfully his default is happy and it's a million times harder when he's whiny which isn't often, if you have a default whiny child I'm sending even more love and hugs your way as those times for me are extra tough.
Like I said this works for me but I've no idea if it would work for you. I'm not posting to give advice, just solidarity, it's fucking hard, it's utterly exhausting but its my mindset of leaning into and embracing the crazy that's been the most helpful thing for me. I'm a single mum and aside from school they are with me every other minute of every day. I fully accept my wee DS is crazy, hyper and life is never gonna be quiet and boring with him around!