When you've defeated monsters the size of buildings, the stark contrast of a foe being your size and stature should immediately set off alarms in your head for the battle to come. Typically, this archetype of fight will be "you, but better." These foes are perfect examples:

Vergil: Perhaps the earliest, but not the most true, Vergil remains one of the "bat themed heroes" of this archetype. Vergil is Dante's twin brother, and his core style of fighting is not unlike Dante, his brother. While you spend the majority of DMC 3 fighting inhuman abominations, many of which are gigantic, you're then hit with the immediate stark contrast of your literal identical twin\* brother, who also uses a sword, standing before you. He proves to be the most difficult encounter throughout the game and you face him multiple times. He even gets upgrades and new weapons similar to you.

\*I'm aware him being identical was retconned later

Artorias of The Abyss: \*The\* primary inspiration for the meme at the start of the post. He's a similar size as you, fights you 1:1 and proves to be more difficult than many previous encounters, of course those being eldritch abominations, gigantic demons and whatnot.

Jetstream Sam: Basically the same deal as Vergil, but serves as a contrast to huge cyborgs and robots instead of hulking demons

Lady Maria: Bloodborne has several examples but this one is probably the most difficult and thematically relevant.

Krauser: But pretty much only the RE4make version.

[Video game trope] The Captain