Slimes do spawn in mangrove swamps, but any regular swamp biome will do. If you are looking for these huge green blobs of slime in your swamp biome, there may be a few things you will have to do first ...
The Mangrove tree is a unique tree that was added into Minecraft with the 1.19: The Wild Update. It grows in the Mangrove Swamp biome and you can use it to get wood or add aesthetics to your build.