Look up the Chinese Web novels "Warlock of the Magus World" and "I shall seel the heavens"
Warlock is an Anti-hero kind of guy who isn't really evil but does only what profits him and he gets very powerful in the process.
Seal the heavens is kind of like the perpetual path of getting more powerful, while the type of enemies he gets and provokes are also more powerful. The MC here has a better moral compass than the warlock guy but still pisses of most powerful guys and girls. There is also more humor.
Well generally speaking almost every xianxia, wunxia (chinese novels) have op mc that surprise others. If you want something more hmm how to say it complex i would recommend mahouka for example or the warded man if you prefer sth not asian. If you would like to try manga I recommend kingdom.
Well, depends on the kind of power. The MC's own power or the power through his subordinates. Or if he can outthink his adversaries.
The MC from Release that Witch gets his power through his intelligence and loyalty of the witches. He himself is a weakling in the grand scheme of things.
Well I read release that witch and it is not typical chinese novel. This nover is pretty ambitious, I mean the explanations of system, down to earth protagonist, pretty unique novel, so no wonder that it has high rating. From chinese novels I would recommend Heavenly jewel change. Very wrll decribed world, not a bullshit with higher realms. Also main character is cunning and not arrogant young master. On top of that harem is well done, with actual females development. On my personal note i also enjoyed against the gods but many people hate it. I think it is worth checking. Fights are amazingly described imo and powers are also outstanding. Super confortable to imagine it.