Bulbapedia says no; it applies only to to Legendary Pokémon, Mythical Pokémon, and Ultra Beasts, except when in X and Y, there are some I'd be interested in looking at:
Nidorina, Togepi, Tyrogue, Smoochum, Azurill, Chingling, Mime Jr., Riolu, and Mantyke all appear in those games in the wild, so I wonder if those all appear with 3 perfect IVs too. I've never owned the game and it would really shock me if that were true. Bulbapedia implies this was once a thing and was amended.
https://bulbapedia.bulbagarden.net/wiki/No_Eggs_Discovered_(Egg_Group)