An NFT doesn't include the assets, it's just a receipt ID.

For a recent example, Riot has just released a bunch of tie-ins for with other games. Like the character Jinx is now in Fortnite. You could use an NFT that says this person owns the Riot character Jinx and thus the Fortnite developers could let you pick the Jinx skin in game.

Although a realistic example I think it would be stupid to do in practice because why would would Epic want to give away Jinx for free just because you bought it from Riot? Then there's a much smaller advantage of having the tie-in, sure you could get cross-play between Riot games players and Fortnite players but you also lose on a quick cash win of getting Riot fans to buy a Fortnite skin.