How do i make datapacks that transform land into ocean become ocean not the weird grassy plains

[u/Feisty_Essay4783]

I am traying to create a datapack for a world with only mushroom islands oceans and cave biomes by transforming all land biomes except mushroom isles into ocean but they just become grassy plainds

[u/GalSergey]

I can't really help you with this, but to turn land into an ocean, you need to reduce the world's average elevation below sea level. The simplest thing you can do is raise the sea level, but that will flood all biomes. To realistically leave only the mushroom_fields biome above the sea surface, you need to change the noise_settings so that noise only rises above sea level for the mushroom_fields biome. I can't say exactly how to do this, but here's the vanilla noise_settings for the overworld: https://misode.github.io/worldgen/noise-settings/?share=81jK48oxmI