To celebrate the launch of Pokémon Legends: Arceus, Niantic has announced that new avatar items inspired by the main characters’ outfits from the game will be available to all Trainers in Pokémon GO!

New Avatar Items Inspired by Pokémon Legends: Arceus coming soon!

Trainers,
To celebrate the launch of Pokémon Legends: Arceus, new avatar items inspired by the main characters’ outfits will be available to all Trainers!

Please be aware of your surroundings and follow guidelines from local health authorities when playing Pokémon GO. Upcoming events are subject to change.

Source: https://pokemongolive.com/en/post/legends-arceus-outfit/