The heavily rumored Horizon Forbidden West DLC is real and it's coming in April 2023, according to website Insider Gaming, which understands that the add-on will be called Burning Shores. An announcement of the DLC was teased by prominent leaker "The Snitch" in a Tweet, which appears to feature a "focus" from the game overlapped on a map of the area where Horizon Forbidden West takes place in the United States.
— The Snitch (@insider_wtf) December 6, 2022
This lines up nicely with actor Lance Reddick, who plays Sylens, revealing back in September in a now-deleted Tweet that he was doing additional performance capture for Horizon Forbidden West. Coupled with the fact that "The Burning Shores" are referenced multiple times in-game, I think we have ourselves some DLC inbound. Of course, Horizon Zero Dawn also received DLC support in the form of The Frozen Wilds back in 2017, so there is certainly a precedent here from developer Guerrilla Games.
Could PlayStation make an appearance at The Game Awards on December 8th to announce The Burning Shores? We'll see.