These are all found within the system-specific apps, which you can download from the eShop. Subscribing to Switch's online service lets you access a library of old N64, SNES, NES and Genesis games, like a Netflix for Nintendo games. The Legend of Zelda: Ocarina of Time is among the most beloved games of all time, and you can play it on Switch. However, one major multiplayer game will work without a subscription: Fortnite is playable online even if you don't have an active online subscription. The most basic perk of Nintendo Switch Online is online multiplayer gaming - if you want to visit a friend's island in Animal Crossing: New Horizons or battle your buddies in Super Smash Bros. The Expansion Pack tier doesn't add any restrictions for subscribers on family plans, so it'll work the same way as it does on the basic tier. It's possible for the administrator to set other accounts in the plan as 'supervised,' letting them restrict eShop purchases and viewing, as well as reviewing sign-in history.
