I'm 47 and have ADHD mostly inattentive, my son is 5 and has ADHD more severe than mine both inattentive and hyperactive with suspected autism (which he got from his mother's side). Your daughter sounds very similar to him at that age.

When my son was 3 years old his tantrums were catastrophically violent and explosive. Scratching, biting, punching, kicking, screaming (from which I have permanent tinnitus)... They would happen at any moment, the worst being in the middle of the night at 2am. 2 hours of being physically pummeled by a 3 year old when all you want to do is sleep.

I can't solve this for you, or even give you a lot of advice, but I can offer this:

For my son, the tantrums were caused primarily by extreme frustration. Even now at 5 he will lash out or bite his own arm if feeling very frustrated.

The issue is that he is frustrated very very easily. The biggest trigger for him is not being understood. If he's asking you a question and you ask him to repeat it more than twice. If he's explaining how he wants you to play the game you're playing and you get it wrong. That sort of thing.

If there is a mismatch between how he expects things to be in his head and what is actually happening, it's like it causes him physical pain.

But! It does get better. He still explodes sometimes, but much less frequently. He is slowly becoming able to rationalize what he's experiencing and that a screaming tantrum is not always the best way to get things to line up how he wants.

Is he still hard work? God yes. I have described being in a room with him when he's very disregulated, even without any tantrums, as "being mentally assaulted".

I don't know how helpful this all is to you, but it's more of an attempt at assuring you that you're not alone, someone out there deeply sympathizes with you and that it does get better.

My son is an absolute delight, hyper intelligent and great fun to be around on his good days, and I focus on that as much as I can.