That physical versions of Nintendo Switch 2 Edition games will include the original Nintendo Switch game and its upgrade pack all on the same game card (i.e. they are exclusively Nintendo Switch 2 game cards, with no download code). Alternatively, some publishers may release Nintendo Switch 2 Edition games as download codes in physical packaging, with no game card.
That is the maximum size, but it’s also the most expensive size.
Street Fighter 6 is 60GB on Steam, so they probably could put it on the 64GB card if they wanted to. But it’s going to be a download.
Bravely Default is only 11GB, but it’s going to be a download too. Probably because it’s a much more niche game that SE doesn’t expect to sell a lot of units of. It’s probably more comparable to an indie game where the physical release is more of a collector’s item for hardcore fans than the main way they expect people to play the game.
It’s a combination of Nintendo following their tradition of using expensive and obscure formats, publishers being cheap, and some combination of publishers/devs for not optimizing for storage.