It seems that four-player co-op will be possible in Gotham Knights.
A Reddit user noted that the description of the game on the PlayStation Store has changed. The description now states that four-player co-op will be supported via PlayStation Plus. Earlier it was announced that the game could only be played by two players together.
In Gotham Knights, players take on the role of Nightwing, Robin, Red Hood or Batgirl, shortly after the death of an important figure in Gotham. The game should have a “dynamic and interactive” open world that will house famous villains such as the Court of Owls. The game is being developed by Warner Bros. Games Montreal, led by creative director Patrick Redding, who previously directed Splinter Cell: Blacklist and Splinter Cell: Conviction.
Gotham Knights releases on October 25 for PlayStation 5, PlayStation 4, Xbox Series X and S, Xbox One, and PC.