Trying to create a skyblock datapack

I've never made a datapack before and trying to figure out how it works... Is there a resource I can get to see what the code looks like in the base game so I can try learn how it works? For my skyblock datapack how would I go about removing all the blocks in all three dimensions while keeping biomes and spawning all the same? Cheers, ill take any tips, just trying to figure out how to even learn this stuff.