Joker: Folie à Deux director Todd Phillips confirmed in an interview during an early press screening of the highly anticipated Joker sequel that the film is not connected in any way to the newly emerging rebooted Multiverse films of DC Studios being led by James Gun and Peter Safran.
Collider’s Steve Weintraub reported having been in attendance at the screening that Scott Silver; Joker’s screen writer, that the project had been far into development before Gun and Sanfran’s take over. As a result the studio executives made the decision to keep Joker: Folie à Deux on the path it was already on as an “elseworlds” project much like the first film when it was released durring Zack Snyders tenure as head of the DC cinematic universe. The elseworlds films are more or less the creations of independent film to the DC universe that function as their own stand alone stories and continuity.
What Phillips means is that the Joker doulogy exists outside of the DC connected films just like the Batman film Matt Revees made. Along with that Gunn and Safran had no part in any of the decisions made for the final film. Both Phillips and Scott stressed that as an important aspect of the film. Consider Joker: Folie à Deux the final send off to old DC but not the start of the new era.
Joker and its sequel were exclusively Phillips’s vision and will be its own unique continuation of the adventures of this Clown Prince of Crime Author Fleck.