Sky High

Sky High is a small data pack that does one thing: Increasing the Overworld height from -64 to 320, to -64 to 1024 blocks (1088 blocks total).
This data pack should be compatible with any world, but always back up your world first, before enabling or disabling this data pack.

FAQ:

Q: What happens if I remove this data pack after I built beyond the vanilla world height?
A: Upon world reloading all blocks placed above vanilla build limit will be gone.

Q: When joining my world I get a warning about experimental settings, is there a way to disable that?
A: Yes, if you are using fabric, you can use this mod.