What is the most severe punishment a ruler can inflict upon a young man who engaged in acts preliminary to sodomy and caressed his friend over clothes, then repented, and is now in lands that implement God's law, fearing his matter might be exposed?

The precursors to indecency are forbidden by the consensus of Muslims. We congratulate you on repenting from them, and we hope that repentance will be accepted from anyone who repents sincerely, abandons the sin, regrets it, and resolves not to return to it. The repenter should perform many good deeds, conceal themselves, and frequently supplicate with "O Allah, cover my shortcomings and calm my fears," and seek forgiveness, for Allah is Forgiving and Merciful. As for the punishment in such a case, it is ta'zeer (disciplinary action).