If you found a standalone NSP labeled "Sonic Mania Plus," it usually contains the base game + the DLC + the update all in one package.
: Added native support for the Switch's capture button, allowing you to record the last 30 seconds of gameplay. Sonic Mania Plus Switch NSP UPDATE
: Seek out "Gigantic Rings" hidden in levels to enter 3D Special Stages. You must catch the UFO to earn one of the seven emeralds. Top 10 Sonic Mania Stage Mods If you found a standalone NSP labeled "Sonic
: Adds Mighty the Armadillo (Hammer Drop ability) and Ray the Flying Squirrel (Air Glide ability). You must catch the UFO to earn one of the seven emeralds
Sonic Mania Plus goes on sale on the eShop for $14.99 (or discounted to $9.99 frequently). For the price of a pizza, you get a legal, safe, always-updated copy that supports Christian Whitehead, Headcannon, and PagodaWest Games—the indie team who saved Sonic.