Tom Henderson mentioned lately that Call of Duty: Warzone 2 will have a second map that is similar to Rebirth Island. This map is expected to come out after the initial launch. The source for this leak was that a playtester noticed a second map in the game menu, though it was inaccessible.
There is not much known about this second map, but the rumors mention that its size will be similar to Rebirth Island. Rebirth Island is smaller than Verdansk and Caldera, being a great place for close quarter combat. Since the first Warzone actually enjoyed a success with multiple maps, it is not a very surprising move from Activision Blizzard to carry the same method for the sequel.
Release date for Call of Duty: Warzone 2 is currently unknown.