Log into the game from 2 September to 13 October and then you will get the character "Aloy" via Ingame Mail for PS4 and PS5 players.
Log into the game from 13 October to 24 November and then you will get the character "Aloy" via Ingame Mail for PC, Android and iOS players.
This game now supports cross save so you can transition to PS4/5 if you don't want to wait. You need to have reached adventure rank 20 or above to get this.
Still a while away but it seems mihoyo are generously giving everyone a five star character.