Yes and no and maybe.

Some version of stories from all of those universes are part of the current main universe's continuity except Earth-X.

DC has rebooted itself multiple times over the years, so it doesn't really have a strict canon.

DC mythology is as expansive as Greek mythology. Every interpretation of DC is equal in their legitimacy and appeal to a particular audience.

That’s a fancy way of saying they don’t care enough to make the current canon clear to anyone.

@Fanfic Nick i dissagree with not carding enough I have alway found the concept of Canon restrictive and pointless which is why I am a fan of Doctor Who which has no canon at all.