Minecraft datapack custom potions?

There are effects in Minecraft that you can only get by command. There was the idea to add potions with a Datapack that have exactly these effects. But I don't find any recipes in the data folder. Where are the recipes for brewing potions in Minecraft's standard resources? How can you add new brewing recipes?

Unfortunately, this is not possible with data packs. You would have to write a mod.

Recipes can only be changed for the stoves, the crafting table, the stone cutter and the Campfire.

OK thank you then I think of something else