https://wccftech.com/super-mario-maker-2-world-building-tool/

Super Mario Maker 2 allows players to create their own courses, but it doesn’t allow the cretion of full campaigns with a world map. From today, however, this has become possible through unofficial means.

Reddit user techsev created a World Map Builder tool which can be accessed for free online. This tool allows players to string courses together, create alternate paths and much more. The creator is also planning to update the tool with new features in the future. You can see it in action below.