It’s not easy to export all your iCloud data and documents. There’s no single button to click to do this. If you want to quit iCloud, or archive all your data and documents, it’s a complex process. iCloud stores the following types of data and documents:
- Documents, stored in iCloud Drive
- Photos and videos
- Safari bookmarks
- iTunes purchases
Apple has a support document Archive or make copies of your iCloud data which explains how to export or copy all of this data. It’s not easy, and it will take a while, but this document will serve as a good template explaining how to do this for each type of data.
iCloud also stores data for third-party apps, and the only way you can access that data is through each individual app.