Apple has introduced a 2 TB tier iCloud storage plan ahead of the launch of macOS Sierra, which includes a feature allowing users to offload their Documents and Desktop folders to the cloud if their computer doesn’t have enough storage. Priced at $20 a month, this is fairly expensive, and few users will need this much storage. But I guess for those who do want to trust their files to iCloud Drive, it’s going to be useful.
You can upgrade your storage plan from the OS X or iOS iCloud settings.