Custom dimension defined in a data pack cannot be generated and teleport to it.

The "Custom Dimension" is a new feature added in 1.16 Snapshot 20w21a, and became creatable through data packs in 1.16-pre1.

See Minecraft Wiki to learn more about it: [Custom|https://minecraft.gamepedia.com/Custom]

The custom dimension seems doesn't have a level.dat file, and stores in world/dimensions folder. That's I all know.

Thanks a lot.