Male mc's stories usually have rebirth theme rather than reincarnation however I do know some. Hold on
https://www.mangago.zone/read-manga/i_became_the_genius_bastard_of_a_noble_dark_clan/ ( iskai as child ig)
https://www.mangago.zone/read-manga/new_chronicles_of_goguryeo/ ( he only get Isekai when he is asleep, he's alive and do his business at day , iskai as youngest child who's teenager)
https://www.mangago.zone/read-manga/a_villain_s_will_to_survive/ ( the amount of female char in this threatening cuz i don't want this to be harem , so far really good, iskai as professor ,old )
https://www.mangago.zone/read-manga/i_m_gonna_annihilate_this_land/ ( demon lord Isekai as baby - ducking funny)
I'm tired of op fl turns into a baby and get adopted bla bla, i need a great story with op mc who is a boy and we can see his growth (no romance pls, i hate romance in action)