Help!

I am at a loss. My kids are 2,4,6 years old. They constantly throw tantrums. It’s never ending. They never listen. I’ve tried it all. Talking to them, putting them in a time out, spanking their butt. (Please no judgement. It was not hard but it was enough to get there attention). They still talk back and don’t listen. I have sent them to their room all they do is scream and yell and back talk. What else can a mother do??? I’m so done with the attitude issues! If one does it then the other two think they can. It’s ridiculous. I feel like a terrible mother. And I know I’m not. It’s just so draining! Please any advice is extremely helpful and appreciated! 🙏🏻