not isekai:
https://mangadex.org/title/38255/i-am-the-sorcerer-king Solo Leveling ripoff
Rooftop Sword Master
isekai has a lot of OP characters. The ones below are isekai grouped by type
Humor, so it may not be what you want, but the characters are OP:
https://mangadex.org/title/26297/maou-ni-natta-node-dungeon-tsukutte-jingai-musume-to-honobono-suru
https://mangadex.org/title/36123/isekai-de-tochi-o-katte-noujou-o-tsukurou
Humor and Adventure:
https://mangadex.org/title/45903/dungeon-reset
https://mangadex.org/title/33797/lv2-kara-cheat-datta-moto-yuusha-kouho-no-mattari-isekai-life
Adventure:
https://mangadex.org/title/52444/shoukan-sareta-kenja-wa-isekai-wo-yuku
https://mangadex.org/title/23025/souzai-saishuka-no-isekai-ryokouki
https://mangadex.org/title/30744/tensei-kenja-no-isekai-life-daini-no-shokugyou-wo-ete-sekai-saikyou-ni-narimashita
https://mangadex.org/title/22168/legend
https://mangadex.org/title/23042/kuro-no-shoukanshi he's a battle fanatic