The Genshin Impact alternate outfits for Amber, Jean, Mona, and Rosaria will be distributed starting January 27, 2022. People will get them for free. MiHoYo went over the process. All someone needs to do is log in between January 27, 2022 and the launch of the 2.5 update for them. They will be included via an in-game letter. However, after 2.5 they will be unlocked in a different way.
The letter with the costumes will be available for 30 days after you get it. Once you do, you can change the way they look from the character menu. On the main page there, you can press a button to choose between available outfits. Amber, Jean, Mona, and Rosaria’s original outfits and alternate costumes will all be available there when you get them. (So will any paid outfits if you have them and are available.
After 2.5, the costumes will unlock once you get the characters. Of the four characters, Amber is the only person who is earned for free. As people go through the Genshin Impact tutorial, they unlock the four-star Pyro archer. Rosaria is a four-star Cryo character who uses polearms and is available via banners. Both Jean and Mona are five-stars available all the time via Wanderlust Invocation standard and event wishes. (Jean is an Anemo swordswoman, while Mona is a Hydro catalyst-wielder.) So once people would pull one of those three from a banner for the first time, they’d get them and the extra outfit.
MiHoYo also announced that the alternate outfits will be used for the characters in the banner, in-game, and for animated cutscenes after 2.5. The NPCs and banner will show them in the outfits after 2.5. After 2.6, they’ll be in animated scenes. This is due to these outfits becoming the default in China.
Genshin Impact is available for the PS4, PS5, PC, and mobile devices. It will also come to the Nintendo Switch. People can claim the alternate outfits for Amber, Jean, Mona, and Rosaria immediately in Genshin Impact.