It's being billed as a spinoff, which isn't technically wrong, but if it correlates to the 2017 Beauty and the Beast movie, then Disney's new Gaston should serve as a prequel of sorts.
Disney is developing a live-action film about Gaston, the boastful, brawny antagonist in “Beauty and the Beast.”
Luke Evans played Gaston in Disney’s 2017 live-action “Beauty and the Beast” remake but he isn’t expected to reprise the role. Instead, the studio is planning a fresh take on the character with a new leading man.
Source: Variety