Since this Joker origin movie will remain separate from the DCEU, it won’t star Jared Leto in the title role. Instead, Joaquin Phoenix is reportedly in talks to play the Joker in the film. While plot details are currently being kept under wraps, it has been reported that the film will take place in the 1980s and showcase the Joker as a failed comedian who turns to a life of crime after being ridiculed by audiences.

Source:: https://screenrant.com/joker-movies-upcoming-dc-development/