The description that the film will center on a young fairy godmother seems to indicate that the protagonist will be an entirely new character, but perhaps Helena Bonham Carter’s character could still show up.
As of yet, it’s unclear if Helena Bonham Carter will reprise her role as the Fairy Godmother from Disney’s 2015 live-action remake of Cinderella (which is arguably Disney’s best live-action remake to date), but it seems unlikely based on the premise.