Sledgehammer Games and Activision confirmed that Call of Duty: Vanguard will have an alpha starting on August 27th, 10 AM PST till the same time on August 29th, free for PS4 and PS5 players.
Call of Duty: Vanguard is out on November 5th for Xbox Series X/S, PS4, PS5, Xbox One and PC with its world premiere gameplay debuting at Gamescom Opening Night Live on August 25th.
Those that have Call of Duty: Modern Warfare, Call of Duty: Black Ops Cold War or Call of Duty: Warzone installed can access it through the main menu, which will either load you into the alpha directly or prompt a download from the PlayStation Store page.
This is essentially Gunfight but with a much larger map and lives along with a tournament-style approach.