"Metroidvania" is a phrase that describes games adopting action-adventure and platformer genres with an emphasis on non-linear exploration often through an interconnected web of rooms.
"Soulslike" or any of its contemporary phrases describes games adopting the action-RPG genre often with an emphasis on difficulty and play-and-learn observation alongside a variety of other systems (which may or may not all be present, which diminishes what this "genre" even is exactly) like the bonfire mechanic popularized by Dark Souls.
As one should presume from how my post is written, I'm of the firm opinion that these styles of games aren't spearheading any new genre that sets itself a part from others. They've merely incorporated specific mechanics into frames from much broader genres.