One can be skilled at fighting within a set of abstract rules but may fall short if the rules are removed. People are aware of the rules under which they can attack an opponent. These rules can be weaponized and used as a shield or to bring in reinforcements (the authorities) against the opponent.
Most martial arts come with rules. For example in boxing, there should be no blows below the waistline, no kicking, and no pounding on the opponent if they fall to the ground. Mixed martial arts (MMA) has those rules drastically liberated, but still, some are retained. Then there is street fighting with no rules. Knives, sticks, guns, gangs of friends, everything could be used to subdue an opponent.
Depending on the rules that govern the situation, a person might choose to fight or flight. What's the worst that can happen within a set of rules? Many people would easily take on Mike Tyson in a match of thumb wrestling or chess, but not so much in boxing.
Social interactions aimed at increasing one's social status are a form of martial arts. They come with a broad set of rules. A skilled social status fighter can leave lifelong psychological scars on an opponent or even cause their suicide. This can happen within the rules and socially acceptable behavior.
A common theme in dealing with bullying is to change the game and fight back within your preferred set of rules.
This can make some bullies realize that would-be-victims may have other tricks up their sleeves so attacking people in any way brings consequences. More likely though, it just makes the bullies go for even lower hanging fruit. Until they eventually grow up and stop competing for social status. By that time they will have left a trail of damage on society.
To sum it up: figure out a way to change the game and let the bully experience you on your home turf. Get extremely good at something useful, then figure out a way to use it in your defese.