interesting thread as you could be describing my 7yo DD who has always been like this! I have sought assistance via the school and had some help with parenting strategies. DD will scream abuse at me, throw things at me, slam doors and then bang on them. She runs away, she won't brush her teeth, or let me brush her hair, or put her shoes on, or turn off the tv... the list is endless. Total and utter defiance all the way to any simple request.
The main thing is to try and stay calm yourself but far easier said than done, I know from experience :( I have also been told to hug DD and tell her that it is ok to be angry. That is not always possible though...... I generally leave her to calm down , by which time you would think she was a different child.
DD is usually lovely at school, but totally and utterly defiant with me and nearly every request from me, is met with backchat, rudeness and defiance.
I was at the end of my tether when I asked for help, so don't let yourself get to that point.
PDA was also suggested to me on here and DD does tick a lot of the boxes but the SENCO at the school wasn't interested in that theory.
Time Out never ever works with DD. A count to 5 usually works, but you must follow the threat through (no tv, early bed, no screen time, whatever you say you must see it through)
Let them make decisions as well within reason, so instead of saying Wear This, give him 2 tops/trousers and ask which ones he would like to wear. Giving them a small amount of control within reason, usually helps as they don't feel like they are being told what to do. Maybe try 2 toothbrushes and ask which one he would like to use. I got a flashing one and a battery one. If it is food, again within reason, offer a choice of sandwich or cereal or snack.
Also giving plenty of warning... the clock hand is on 5, when it gets to 6 then the tv will go off, that is in 5 minutes.... it seems to help a lot with DD if she knows what is going to happen and when so no surprises.
It's not about letting them take control, but it's about letting them think that they have some control over their life, when in reality you are still getting what you want.
I had a lot of help from the local Family Support Network, via the school, so it may be worth approaching your DS school to see if there is any help available.