Among the developing DC Films projects that feature Harley Quinn in some capacity right now are Suicide Squad 2, Gotham City Sirens, and Harley Quinn vs The Joker.
The reports also emphasizes that Birds of Prey will not be a Harley solo movie, but instead feature multiple female villains and superheroes/antiheroes alike.
According to The Wrap‘s sources, Birds of Prey in particular is a project that Robbie has taken a personal interest in.
The Wrap reports that Suicide Squad 2, Harley Quinn vs The Joker, and surprisingly Birds of Prey are the three mostly likely candidates for Robbie’s next onscreen appearance as Harley Quinn.