Being a good example for me also means, to stop bullying and in general exploiting of weaker ones.

I also do martial arts with kids. It teaches them how to fight, but more importantly, not needing to fight, especially not weaker ones, to feel superior. If you know you are strong, you don't have to show off. People with low self esteem does that.

Yes, but stopping is not enough. It will just move beyond your back. It is also important to actively teach positive problem solving, deal with underlying reasons for bullying etc.

The same for victim or maybe even more importantly. You have to actively teach the kid behaviors that makes it less likely bullied, in situation when the kid is not bullied right now. Even if you are naturally assertive, the kid may not be and you gotta actively work with it.

Doing things and explaining them if needed, are going together for me.

And didn't I say I do martial arts and it is much more about fighting? If done right, the agressor stops doing so as he don't need it anymore to feel confident and the victim walks upright and does not have written "victim" on their head anymore.

When I need to teach the small kid to hold the toy while the other is trying to take it away, I wont be able to teach that just by explaining while role-modeling. The same when I need to teach a bit older kid to relax and swear back.

Second, no, one intervention is not enough, for neither kid. It takes repeated interventions as behavior goes away and comes back sometimes in different form. It is not just about walking upright either.

These are strong habits in both children when talking about repeated issues. And aggressors motivation are more complicated then just confidence (situation in family that wont go away, parents who encourage aggression etc). In martial club, you need to stop the behavior while in club (not accepted here), in home you deal with it repeatedly and need to change it in situations you don't control at all and know only half of.