Marvel and DC have to run a business around a franchise of instantly-recognizable characters, so it makes sense that they mostly hire artists who draw in a “superhero” style for consistency. It’s possible to change your style — I did quite a lot in college — but there’s nothing more heartbreaking than seeing an artist change they unique personal vision just to try to get a job. If you find yourself having to do this to get closer to a “house style”, then you might want to reconsider how passionate you’d really be about the job if you did get it.