I’m constantly seeing videos on Facebook of guys using crazy mods for Breath of the Wild that show Link replaced with all sorts of random characters and other enemies in the game also being replaced. How do you install these mods on the Nintendo Switch version of the game?
The mod videos from Breath of the Wild are actually from the PC version of the game. Yes.. weird considering this game is a Nintendo exclusive. There is a Wii U emulator for the PC and people have not only been able to get Breath of the Wild to run well on PC, but they have been able to manipulate the game in ways that let them replace in game models with custom models like the ones you have seen in the videos.
To answer your question directly, it is not possible to install mods for Breath of the Wild on the Nintendo Switch and it is unlikely that it will ever be possible to do this.