I have 2 DC like this - one of them is a lovely teen who no longer hits anyone with sticks or anything
The other is still in this very wearing phase. He is also 5 so don't think it goes on forever. With DS1 I found it improved at 6 and got much better at 7. And I barely knew anything then.
You will probably get more ADHD specific help in the SEN section.
In general, what I've learnt over the years is that with this kind of thing, what you do in the moment is of very little consequence, which is exactly opposite to what most parenting advice will say. Of course there are supremely unhelpful things to do in the moment - reacting in kind, physical violence - I'm sure you're not doing that though. (I was advised to do it a few times - I am glad I didn't).
But really, it's not about the moment. It is about working slowly on behaviours one by one and consciously building in support and scaffolding for the positive opposite expectation. And building skills in areas like impulse control and emotional regulation. And understanding their stressors and working where you can to reduce them over the various domains of their life, and doing that with their involvement so that they also learn the skill of self-advocacy and how to assess and address their own stress levels throughout life.
Understanding ADHD will help a lot. Russell Barkley has some brilliant videos on Youtube explaining so much. There's also a good OU course on ADHD.
Understanding how the brain moves between three different states - cognitive / emotional / survival - this helps a lot. There are different models explaining this, I like the one by Conscious Discipline as I think it's the best explanation and Becky Bailey is a really great teacher:
(BTW, something I didn't understand for a very long time - all the "How To Talk" type stuff may help when a child is in the emotional state, which they often are because their brains aren't mature, but nothing helps if they are in the survival state, the difference is that NT children very very rarely enter the survival state, certainly past the toddler years.)
Ross Greene/The Explosive Child can also be really helpful.
Since you can't realistically address behaviours in the moment you need to make a plan of action to start working on the root causes. To do this you start by writing a list somewhere of the most common recurring behaviours, situations or expectations you (he) are having difficulty with. Then pick a couple to work on. By working on, you're being a detective to try to work out what the root cause is, whether there is a stressor (or multiple) and/or what skills are lacking. Maybe break it down if it's actually multiple things. Then you'd work on those skills at neutral times. You also look at what your positive expectation is and work on ways to encourage and reward that, break it down into manageable steps, etc. There is a good course on Coursera called The ABCs of Everyday Parenting which has a lot of good techniques.