In Echoes of Wisdom, the Great Fairy needs your help. And, in order to be the most stylish person in Hyrule, there's no way you can turn her down.
The Great Fairy's Request Side Quest is only available once you've completed a certain number of tasks for the Great Fairy, which means you need to spend a lot of rupees. As such, you likely won't be doing this Side Quest until near the end of the game.
Where to find The Great Fairy's Request Side Quest
The Great Fairy's Request is located in the Great Fairy Shrine in the middle of Lake Hylia. That means you need to clear the Stilled Lake Hylia Rift to access the Shrine.
Not only that, you also need to increase Zelda's accessory slots to the maximum amount. This is a pretty expensive endeavour, so the sooner you start saving your rupees, the better.
Once you have all five accessory slots, leave the shrine and return at any point to find a treasure chest in front of the shrine. Open it for a Might Crystal, and the Great Fairy will appear.
The Great Fairy will start scolding Zelda before eventually admitting that she has a way of making a useful accessory that will help you get all Might Crystals in Hyrule. However, she wants a piece of well-crafted jewellery in return.
She will tell you of a Gerudo woman who is known for her skills, and you'll be given The Great Fairy's Request Side Quest.