Alternate outfits for Jean, Amber, Rosaria, and Mona
If you want some free Genshin Impact outfits, all you need to do is log in anytime starting now through update 2.5 (when it is eventually released).
There’s not really a catch either, because the developer notes that even after update 2.5, “the Alternate Outfits will be unlocked automatically when Travelers have the corresponding characters.” So either way you’re going to get them, just note that you can snag them right now if you happen to log in and redeem the in-game mail that’s sent to your account (which has a 30-day timer on it after it’s sent). Also note that of all these outfits, Amber is the only free character (one of the first you unlock in total as a free-to-play player): the rest are premium, and vary in rank (Jean and Mona are rarer five star characters, while Rosaria is a four star).
To unlock them, all you have to do is redeem them via the mail, then go to the character screen, head to “dressing room” (a side option triggered by pressing in the right stick on consoles), and select them. Also don’t forget that the Fleeting Colors event is running right now, too.
The full instructions/details for the free Genshin Impact outfits are located here.