If the data pack has the correct format, it will be included in the world.Click “Done” and continue creating your world, and then click “Create a New World”.Move the data pack to the right side of the screen by clicking the triangle on its icon.Drag the data pack into the Minecraft window.Create a new world and click on the “Data Packs” button.Here the developers have provided that the data packs can be set either in a new or in an already created world: Method 1: Installation when Creating a New World How to install Slime Rain Data Pack Installation for Single Player
