All themes include the ability to present a hero video on your homepage.
You'll need to use a homepage cover layout. In Customise > Theme Layouts, tap the edit layout options on the layout you're using and you'll find a Vimeo URL field in the options drawer.
Use a Vimeo URL belonging to a Vimeo Plus or Pro account (Vimeo don't allow background/playerless video streaming through their free account).