Drop rate by level
Do higher level enemies have a higher chance to drop items?
For example, if I'm farming Dragon Fangs, would it make more sense to farm in Fuyuki or France?
Solution 1:
In Fate/Grand Order, item drop rates are per-enemy in each quest, and the rates are set on the server. Enemy level does not correspond to drop chance at all, and drop rates are specific to each quest.
Therefore, every quest has its own possible selection of item drops, and these drops are dependent on the enemies that appear in the quest. Typically each enemy type is associated with a selection of items (e.g. Werewolves and Yggdrasil Seeds/Chimeras and Claws of Chaos).
There are multiple attempts at crowdsourcing to determine the actual drop rates per quest (and therefore calculate the AP needed per drop at any given node). For the most efficient farming locations, I recommend Gamepress or consulting the spreadsheet. As noted in a prior answer, events are typically the best way to obtain certain items.
Solution 2:
Unfortunately, no. Higher levels mean nothing to drop rates. Visit this link on how the drop rates work and how many you can get after a certain number of plays.
Tip: if you want to farm for something, look for a quest where there are less items on possible drops so you have a small but higher chance of getting your item. Also, the best way to get items is from events.