Like One Piece, hmmm. That is a difficult one.
Luffy is the main character and the guy who has to save the day in the end, he's the most powerful one. At the same time he's a complete moron, like how he drowns a lot, or only thinks about eating, has zero clue about navigation, etc. This is important to the One Piece story because if Luffy was a genius, he'd not need his friends after all.
It is fun to watch a powerful idiot in a manga/anime, but "idiot MCs" usually do not work well in a novel at all. After all, a novel usually shows us a lot about what characters are actually thinking, and in One Piece you can't tell anything at all, Luffy is acting by pure instinct most of the time.
So what makes One Piece work in a manga / anime, is very very difficult to pull off in a written novel. I currently can't think of one.
"Release that Witch" would be a candidate, which has a MC incapable of doing magic, and he has to depend on witches (which he rescued or otherwise helped) so that kind of puts a lot of focus on his harem, but... he's still the sole powerhorse as he brings technological knowledge and scientific methods. And in the end he does learn magic regardless after all.