Aside from the loot boxes, Genshin Impact's other big influence from free-to-play mobile games is a system that limits how often you can get rewards from certain activities. It's called Resin, and it's used to open up withered flowers that appear after defeating some bosses or completing the Ley Line challenges you'll find listed in your Adventurer Handbook.
It sounds limiting, but Resin recharges fully once per day and you get quite a bit of it, too. So don't just let it sit there because once it caps out you'll stop generating more. At higher levels, there's specific activities that use quite a bit of Resin at once that you might want to save for, but starting out, it's absolutely worth it to burn through all of it as quickly as possible. It'll slowly recharge over the next 24 hours anyway.