I'm currently trying to ascend from AR 45 to AR 46, but I was wondering if it's effective to lower my world level to complete the domain. if I had the answer I would lower my world level, but I don't want to have to wait an entire day to revert it.
2 Answers
It does not lower Domain difficulties.
World levels affect the "world". Domains are not included.
The world level affects the level and drops of Monsters, Ley Line Blossoms and world Bosses(only in the world, not in domains).
Examples:
Included: Monster Camps, Cryo Regisvine, big bad white wolf, Ley Line Blossoms
Excluded: Any Domains, Stormterror, Childe, chest rewards
Everything where you got to choose an instance, the world level doesn't matter. Even if it's only one instance to choose.
See also Genshin Impact Wiki - Adventure Rank
Domain drops are only affected by your AR, since AR is what unlocks each level. This means that trounce domains, artifact domains, and ascension material domains are not affected by you lowering your world level.
Lowering your world level will decrease drops/drop quality of open world domains and mobs though.