This game isn't succeeding primarily because of great marketing, franchise, or blind loyalty to Nintendo (though all of those help!).
It's succeeding primarily because it's the follow-up to a game that critics and players universally found enormously fun. Before Breath of the Wild previous Zelda entries did not sell this well.
Of course the raw numbers look more impressive for BotW - there are 122m Switch units worldwide (and 30m BotW sales), but the N64 only shipped 33m units worldwide over its 8-year lifespan, and OoT still sold 7.6m copies (with another 6.4m on the 3DS).
The titles you cite (Link's Awakening, Ocarina of Time) also made sales records because they were so good they reached a wider audience. But if you look at historical sales a mainline Zelda entry usually sells 6m to 10m.
Breath of the Wild sold 30 million and Tears of the Kingdom looks to be on a similar trajectory. That's due to the strength of the game design that's broadened the appeal well beyond the typical Zelda gamer.
There are lots adults with college degrees now that are playing this game who weren't even in kindergarten yet (or born!) when the games you mentioned were released.
BOTW and TOTK are still huge successes, but it's not really about great design (unfortunately). If it was, every one of Nintendo's games would be record smashing sellers, but they aren't. They have plenty of games that don't make a dent despite their insane attention to detail. We saw this with Mario Maker 1 & 2, not even cracking 10m copies to this day, and one can't even blame lack of name recognition, it's literally Mario!
Where great design does have impact is on long term word of mouth sales. Which we saw with BOTW and are likely to see here again.
I don't think attach rates offer the full picture. Early on the audience for BOTW was so eager for the game they were buying the Switch just for BOTW. For a period the attach-rate was greater than 100%! But the Switch has broad appeal and the attach-rate of BOTW has declined as more types of gamers buy-in to the Switch. The Gamecube and (to a lesser extent) the Nintendo64 had less success than the Switch outside of core Nintendo fans which naturally means franchises like Zelda would have higher attach rates.
Mario Mario 1 & 2 are both well-designed executions of a concept that appeals to a more limited audience (building and playing user-made Mario levels). BOTW / TOTK hit that sweet spot of widely appealing concept and excellent execution.
Breath of the Wild was certainly the best-seller, but nearly every Zelda game has been a knock-out success selling millions of copies. I think Breath of the Wild is an outlier among them in part because it was out during the pandemic. I know a whole lot of people who bought a Switch during the lockdown and poured hours into escapism with that game.
Breath of the Wild has sold 30.7 million total so far, Tears of the Kingdom sold 10 million in its first 3 days.
Source: https://en.wikipedia.org/wiki/The_Legend_of_Zelda
Tears of the Kingdom is selling crazy numbers even without the lockdown boost. Other factors make a difference but the core of what drives the sale of these two titles is that they're great games people strongly want to play.
Also: https://www.reddit.com/r/gaming/comments/13jurfi/only_8_game...
But this game (and Breath of the Wild) is selling above and beyond previous entries because it's such a great game that its appeal reaches well beyond Zelda's traditional audience.
Contrast that with BOTW at 30 million and ToTK at 10 million in 3 days.