On April 19, Horizon Forbidden West: Burning Shores will be released, which is an expansion for Horizon Forbidden West.
The expansion’s storyline picks up directly where Horizon Forbidden West left off and requires that all main missions in Forbidden West be completed, so this is not a standalone expansion.
However, Horizon Forbidden West: Burning Shores will only be released for PlayStation 5, and a release trailer can be found above. A clip in which the developers explain how to prepare for the expansion can be seen below.