Have you read the BEST new-gen DARK FANTASY, ACTION SHOUNEN MANGA of the 2020s, the peak of human literature, Kagurabachi? If you're looking for a story with a more slow-burning pacing and world-building, but masterfully-written plot, realistically written and interesting characters with great designs, GORGEOUS ART that evolves with each new chapter, MOVIE-LIKE fighting choreography, BEAUTIFUL panelling and composition and NO ROMANCE, ZERO FANSERVICE AND ABSOLUTELY NO SEXUALISATION, ESPECIALLY OF IT'S FEMALE CAST!! OH ALSO IMPORTANT MENTION; DON'T DROP THIS AT CHAPTER 58 (IYKYK), TRUST THE PROCESS OF HOKAZONO-SENSEI'S GENIUS!! GO READ IT NOW!!!
https://www.mangago.me/read-manga/kagurabachi/ (PEAK FICTION)
Other shounen/seinen (mostly action, no romance) mangas:
https://www.mangago.me/read-manga/gokurakugai/
https://www.mangago.me/read-manga/windbreaker/
https://www.mangago.me/read-manga/tokyo_aliens/
https://www.mangago.me/read-manga/gachiakuta/
https://www.mangago.me/read-manga/galaxias/
https://www.mangago.me/read-manga/centuria/
https://www.mangago.me/read-manga/psycho_eyes/
https://www.mangago.me/read-manga/chainsaw_man/
https://www.mangago.me/read-manga/ultimate_exorcist_kiyoshi/
https://www.mangago.me/read-manga/madan_no_ichi/
https://www.mangago.me/read-manga/night_light_hounds/
https://www.mangago.me/read-manga/magical_girl_and_narco_wars/
https://www.mangago.me/read-manga/the_marshal_king/
https://www.mangago.me/read-manga/kai_hen_wizards/
https://www.mangago.me/read-manga/yuusha_izoku/
https://www.mangago.me/read-manga/aftergod/
https://www.mangago.me/read-manga/phantom_busters/
https://www.mangago.me/read-manga/dragon_and_chameleon/
https://www.mangago.me/read-manga/snowball_earth/
https://www.mangago.me/read-manga/utsuranain_desu/
https://www.mangago.me/read-manga/choujin_x/
https://www.mangago.me/read-manga/fool_s_night/
https://www.mangago.me/read-manga/dinosaurs_sanctuary/
https://www.mangago.me/read-manga/tokyo_kaijin_rhapsody/
https://www.mangago.me/read-manga/hero_organization/
Some shonen recs with a male mc and no romance?