Harley Quinn is actually coming Max in the future, no idea about Titans or series like Swamp Thing, Stargirl, or Young Justice.
So far what there will be for Max is
-Doom Patrol
-Green Lantern
-Justice League Dark
-Strange Adventures
-Super High School or whatever its going to be called
-The Reeves Batman cop show
With Batwoman on there I assume in the future the CW/Arrowverse shows will be there once the Netflix deal is done I assume.