make a dimension called CustomEnd,make end like condition,enderman and ender dragon(not tellin' ya how to make here,if interested,comment here) and add your biomes.warning:the biomes will make islands bigger and it is not possible to make a small island with only one biome
You can't
there are mods created custom end biomes in mcreator.
make a dimension called CustomEnd,make end like condition,enderman and ender dragon(not tellin' ya how to make here,if interested,comment here) and add your biomes.warning:the biomes will make islands bigger and it is not possible to make a small island with only one biome