Manifest season 4 brings the series to a satisfying close, but despite the show's definitive ending, there are numerous storylines and mysteries that can be fleshed out further in spinoffs. Following the passengers of Flight 828, which mysteriously disappears and reappears years later, Manifest presents its large cast of characters with an onslaught of questions as they attempt to uncover where they went. They receive visions, or "callings," which reveal that their fates are tied to a date in the future — one they dub the "Death Date." They spend most of the show trying to prevent the Death Date, which eventually finds them reboarding the plane and facing judgment.

https://screenrant.com/manifest-ending-spinoffs-ideas-stories/