While the Emperor was finally defeated for good in Star Wars: The Rise of Skywalker, it's possible that another remnant of the Empire could still return. Following the events of Return of the Jedi and the subsequent Battle of Jakku, the Empire was shattered. While the bulk of the Imperial Fleet headed into the Unknown Regions to be reforged into the First and Final Orders, it's possible another sect headed in different direction entirely.

https://screenrant.com/empire-return-future-after-star-wars-rise-skywalker/