Immortal Coral

Use /gamerule immortalCoral true to enable this mod in your world.
When enabled coral will no longer die when outside of water.
This mod doesn't add any new blocks, so your world will stay fully vanilla compatible.
Works both as single player mod or as server mod, if it's installed on the server there is no need to have it installed client side.

Now also with recipes for in survival (1.18+):

Smoke coral in the smoker to apply a smoke layer on the coral

If needed the smoke can be cleaned off again with a bucket of water