IT: Chapter 2 director Andy Muschietti has expressed his interest in exploring the deeper mythology behind the Pennywise story in a potential sequel further down the line.
Producer Barbara Muschietti, who has worked hand-in-hand with her brother on the past two installments of the IT franchise, confirmed to io9 that Stephen King’s novel, as it is, has been covered in 2017’s IT and the upcoming second chapter.
However, Andy noted that the creepy clown character has a bounteous backstory that could possibly be explored at some point in the future.
Source: IGN.com IT: Chapter 2 Director Says There's Enough Mythology for Future Sequel