Announced via Twitter by IDW this past Saturday morning, not much more is known about the crossover at this point.
Check out the announcement tweet below and stay tuned for more information as the publishers release it.
From Twitter:
If you think you can unlock the gates of hell and just invite yourself in, you must be dreaming. Coming October 2020: @joe_hill and @GR_comics will debut LOCKE & KEY: HELL & GONE - A SANDMAN UNIVERSE Crossover Event, courtesy of @IDWPublishing and @DCComics.