Back to the general education.
When my daughter had reached the right phase of defiance at the age of 5 or 6, I had to think about how to "force" her to do things. (please do not take it literally) what is necessary, but she does not want to do.
So I started counting. That means I told her something she should do, e.g. tidy up her room. If she didn't want to do it, I told her that if I counted to 3 and she still didn't do it, something specific would happen. It was always something she liked even less than what she was supposed to do. I was very creative about that, as you can see from the pacifier story.
This worked so well that shortly after I only had to ask her if she wanted me to count. And since she knew that I do what I say, there was no discussion about it.
I did the same with my son, with the same success.
However, I would also like to point out the problems of this method, so that you do not make the same mistakes as I did at the beginning.
Think well before what you threaten!
Once, but really only once, I threatened my daughter to put her over my knee. I just couldn't imagine that she would go for it. Well, I was wrong. But in order not to lose my authority I had to go through with it. Before there is now an outcry, because of abuse of small children. She was wearing jeans and I slapped her bottom very lightly,
Especially for the fathers of sons is still something very important. The son always wants to compete with you.
Once when we were pressed for time because we had to go to an appointment, my son thought he had me. He knew exactly that I could not threaten him with anything, so I could put him on the right way at that time. I knew that I had to react quickly and decisively. I gave him a slap in the face. Again, no abuse of young children. I struck Blitz quickly but only hit him lightly on the cheek (thank martial arts). It was just to get him out of the consept. Since he had not expected such a reaction, it also worked great. After that he did something confused what I told him.
Those were also the only two times I "hit" my children. It is much more effective to be a little creative and come up with something unexpected. At least that is my experience.