Now, since this system is cartridge-based, you’ll only need to worry about file sizes if you’re buying digital games from the eShop. Those, obviously, need to be downloaded and installed. Physical games will work off their carts.
Interestingly, Dragon Quest Heroes I-II checks in at 32 GB. You’ll absolutely need a MicroSD card to play that one. You should get one anyways, honestly. Just do it.
Article source: https://www.technobuffalo.com/2017/02/20/nintendo-switch-game-file-size/