I'd suggest looking at Relationship Smarts PLUS (middle school and younger high schools) or Love Notes (an adaptation of RSP for high school and young adults). They teach conflict resolution and many other important life skills in the context of intimate relationships. And, those skills are then transferred by young people to their friends, families, and others. These evidence based programs have evaluations showing reduction in physical aggression and more confidence in their conflict management skills.
Also, Mind Matters: Overcoming Adversity and Building Resilience has shown an increase in emotional regulation, an important part of conflict resolution.
Happy to send you free online review copies of any of these programs.