It's not based on a true story. The plot and characters of Bully 2001 were created by the imagination of the writers and not drawn from real-life incidents. Usually, such fictional works are crafted to entertain and engage the audience with an invented narrative.
I'm not sure specifically which 'the bully true story' you're referring to as there could be many. It might be about a real - life incident of bullying, perhaps detailing the experiences of the victim, the actions of the bully, and how it affected those involved.
The movie 'Bully' is purely fictional. It was created by the imagination of the filmmakers and doesn't draw from real-life events. The story and characters were crafted specifically for the film.