Genshin Impact 1.4 introduced a mechanic that many players have wanted for a long time, allowing them to change their world level. This means that if you hit a new Adventure Rank and didn’t realise your World Level was about to go up, you can change it. Rejoice, Traveler.
To get access to this, you will need to reach World Level 5, so keep that in mind, it is not something you can do from the start of the game. You will also only be able to reduce your World Level by 1, you will not be able to jump back down to a super low World Level.
You can change your World Level by open the Paimon Menu and then hit the Info symbol on your name card. Switch the World Level to the one you want, and after you change it, it needs to remain that way for 24 hours before you will be able to change it again.
When players reach Adventure Rank 60, they will be able to convert earned experience into Mora at a rate of 10 Mora per experience point, so many players will want to hit the max rank, then drop the World Level as a way to passive earn some extra Mora.
Dropping your World Level means you will get to fight weaker enemies and get faster clears and boss fights, but it also means you will get lower tier rewards, less experience and ascension materials, and will need to wait out that 24 hour cooldown before you can switch it back.