https://www.mangago.zone/read-manga/i_ll_be_the_matriarch_in_this_life/
these fit your desc but they do not reincarnate into a child, but instead into teenagers/adults:
https://www.mangago.zone/read-manga/actually_i_was_the_real_one/
https://www.mangago.zone/read-manga/the_lady_s_butler/
https://www.mangago.zone/read-manga/princess_wars/
https://www.mangago.zone/read-manga/the_reason_why_raeliana_ended_up_at_the_duke_s_mansion/
https://www.mangago.zone/read-manga/anyone_can_become_a_villainess/
https://www.mangago.zone/read-manga/higeki_no_genkyou_tonaru_saikyou_gedou_rasubosu_joou_wa_tami_no_tame_ni_tsukushimasu/
https://www.mangago.zone/read-manga/reminiscence_adonis/
https://www.mangago.zone/read-manga/the_villainess_reverses_the_hourglass/
https://www.mangago.zone/read-manga/the_small_sage_will_try_her_best_in_the_different_world_from_lv_1/
https://www.mangago.zone/read-manga/i_ll_be_the_matriarch_in_this_life/
https://www.mangago.zone/read-manga/shadow_queen/
^ ^ ^ ^ ^
- Reincarnated/ traveled back in time
- Kids who are way too OP (￣∇￣")
So currently obsessed with reincarnation, but Im finding a powerful fml that got reincarnated as a child and still possess their power, just like the evil empress, skmeone reccomend me somethjng