Pokémon Legends: Arceus — How to get Alolan Vulpix
The Ice-type Alolan Vulpix isn't native to the Hisui region. However, you can get one in Pokémon Legends: Arceus if you complete a specific sidequest.
White Vulpix Arceus Alolan Vulpix Sidequest Alpha Garchomp Alolan Ninetales Arcues Alolan Vuplix Alolan Vulpix
Source: imore.com