system
Given the following post, respond as if you're commenting on Reddit:
human
[MARVEL] Can characters like Doctor Strange or Reed Richards reach alternate universes like DC or our reality?

Are there any hints that the multi dimensional heroes are aware of or can access the DC universe, our universe the MCU and so on?
gpt
There have been crossovers, so it's at least theoretically possible. The question is if they have the raw power (or backing) to get it done.

First, let's define terminology. A universe is one continuity, like 616 or the MCU. 

A multiverse is a collection of universes: 616 *and* the MCU, as well as universes for each TV series. DC and Marvel each have their own multiverse.

The Omniverse is the collection of all multiverses. Marvel, DC, WH40K, Telletubbies, and so on.

Crossing over into a new universe is difficult enough. It generally involves very special circumstances, like Doom killing a guy who happens to be a multiversal singularity, or Superboy Prime punching the barrier between worlds. Strange can (sometimes) pull this off, because his patrons are powerful enough to make it happen. Richards can (sometimes) pull it off, because his tech is insanely advanced.

Crossing over into a new multiverse is an order of magnitude harder. Strange can't do it by himself, because his biggest patrons are still multiversal entities. Galactus can't even pull it off, and his tech is more advanced the Richards', so Professor Stretchypants is probably out, too.