Yes. We have published research in which early adolescents in the United States and in Pakistan have benefited from a forgiveness intervention. Here are the references to these works:
Gambaro, M.E., Enright,R.D., Baskin, T.A., & Klatt, J. (2008). Can school-based forgiveness counseling improve conduct and academic achievement in academically at-risk adolescents? Journal of Research in Education, 18, 16-27.
Rahman, A., Iftikhar, R., Kim, J., & Enright, R.D. (2018). Pilot study: Evaluating the effectiveness of forgiveness therapy with abused early adolescent females in Pakistan. Spirituality in Clinical Practice, 5, 75-87.