The goal for a child is not to win a fight. It is to never be in one — and to know, all the way down, that they are allowed to say no, allowed to make noise, allowed to run, and allowed to tell someone.
For the youngest kids this looks like games. Voice, distance, noticing, getting to a grown-up, and breaking free from a grip. It is loud and it is fun and it does not involve teaching a five-year-old to be afraid of the world. Fear is not the lesson. Capability is.
As they get older it grows up with them. Teenagers get the real material: how situations actually escalate, what a bad party looks like an hour before it goes wrong, how to leave without losing face in front of friends, and what to do with your hands when talking has stopped working. Teens can tell when they are being managed, so I do not manage them. I tell them the truth and treat them like it matters, because it does.
The change parents notice first is usually not physical. It is that their kid stands differently, looks people in the eye, and stops apologising for taking up space. That is the part that protects them every day, not just on the worst one.