As you would expect from a free-to-play game Genshin Impact has an in-game shop where you can buy Crystal, the game’s premium currency using real money, which can then be used to get Wishes for the gacha. You can however earn Primogem by just playing the game and it is possible to eventually unlock every character and weapon in the gacha system using them. When you reach Adventure Rank 20 in Genshin Impact you will unlock the Battle Pass which like in most other games has two tracks, a free one and a premium one. If you decide to purchase currency you will be able to advance faster in the Battle Pass than someone who is playing the game completely free.