Those story modes set players on a journey to rescue the Great Zapfish from DJ Octavio, typically by completing platforming stages designed to teach how each weapon type works. Return of the Mammalians is a big step up from its predecessors, Splatoon's Octo Valley and Splatoon 2's Octo Canyon. Plenty more Nintendo franchises could support level editors akin to Super Mario Maker, but Splatoon 3's story mode offers a strong case for Inklings to get their own custom creation platform.
The Legend of Zelda: Link's Awakening remake included a basic dungeon editor, but this was mostly in service of extra objectives rather than creating a community resource. Nintendo opened the floodgates for potential level editors with the release of Super Mario Maker on Wii U, though it hasn't really tapped into that idea beyond a Switch sequel in 2019.