https://www.mangago.zone/read-manga/weak_hero/
male mc, looks pretty weak but nope, he's smart and knows how to knock down someone
https://www.mangago.zone/read-manga/my_school_life_pretending_to_be_a_worthless_person/
Supernatural, male mc, action, he has some deadly power so got no choice but pretend to be weak
https://www.mangago.zone/read-manga/princess_hurricane/
(The licensed version is free in LINE webtoons btw)
It's a comedy with a wacky plot. Princess from another universe and a purple haired high school delinquent get switched places. Princess looks weak asf but has supernatural powers. Her red hair delinquent friend pretends to be super weak in front of her and she actually believes it LOL. The purple hair delinquent dude that takes the princess' place in her original universe is ugly but everyone around him pretends he's not cause they think he's the princess (but after a curse). Might not be what you're looking for but I recommend it.
where the mc (female/male) is rich or famous or strong or rich or smart or ugly but everyone think they arent... if possible in highschool/university.
thank uu