That said, it’s unlikely that IT 3 would be a direct follow-up to IT Chapter Two, thus making this saga a standard trilogy. For one thing, Pennywise is defeated at the end of the sequel, and unlike the last time the members of the Losers faced him, this time the creature won’t be coming back. Even if there was a way to bring back the shapeshifting creature, the Losers Club is now down two members and have moved on their lives, so one can presume that none of those surviving characters would return.
Article source: https://www.cinemablend.com/news/2480365/bill-skarsgard-says-it-3-ideas-have-already-been-discussed