In BotW, Link’s underwear was supposed to be Sheikah underwear that they put on him when they put him in the Shrine of
Port of Zelda
Ganondorf Is Back and So Are Link's Undies in New 'Legend of Zelda: Tears of the Kingdom' Trailer
Underwear BoTW Link 1 - Shrine of Resurrection by Stubbsville9588 on DeviantArt