Horizon: An American Saga is Kevin Costner's long-term Western passion project, and multiple films are slated to be released. The Yellowstone star has been planning the Horizon movies for decades, with its first script commissioned in the late 1980s. In the late '80s and early '90s, Kevin Costner was one of the world's biggest movie stars, with his directorial debut Dances With Wolves winning Best Picture. Surprisingly, he couldn't get Horizon funded then, but the project stuck with him for decades. With his Yellowstone popularity resurgence, Costner is betting on himself by self-funding the project.
https://screenrant.com/how-many-horizon-movies-will-there-be/