For Doomsday I see that the Avengers, Young Avengers and Fantastic Four being the primary focus while Doctor Doom and maybe he could form the Masters of Evil as his allies for this movie with a small tease/maybe other variants from the multiverse

Possibility of Doom going to Loki to cause havoc that starts Secret Wars

Secret Wars will focus on Battleworld that will collide other heroes like the X-Men and a whole of different variants plus who knows other villains like Beyonder, Ultron, King Thanos, Galactus, Molecule Man, Death and several others could have a role within Secret Wars as well

Eventually finding a way for the X-Men to come into Earth-616 and maybe a new home for the Fantastic Four

If the leaks are true then Doomsday is probably going to be one who focus on Doom's World with Dr. Doom as the Protag similar to what Thanos was for Infinity War.

The Thunderbolts, Strange, Maybe Carol, and Sue Storm/Franklin Reed are probably going to be his Slaves with Yelena and Probably Bucky as his heavy hitters. Reed Richards is going to be like his pet Chained up by Yelena and never out of Doom's Sight

At Some point during this film the YA is going to break out of his spell somehow (Maybe they can used that Marvels X-Men universe to bring back Monica to break out Kamala which Kamala then break out Kate Bishop and so long and so long until the entire team, WhiteVis, and Quill are all free from Doom's Spell.)

The YA that are close to the TB are going to somehow break the brainwashing spell the Yelena/Carol are in (So For instance Kamala and Monica are going break out Carol, Kate is going to Yelena, ) Meanwhile the other YA are going to fine Sam so that he can saved Bucky and Walker. Yelena can break out her Dad (if Alexei is still alive post Thunderbolts).

Lol @IronWidowMaikuB i think spidey will be the only one unaffected many are theorizing it’s cause of no way home lol

All I’m hoping for is scarlet witch returns in Doomsday and secret wars