Can I sync files to OneDrive cloud only, and not on my local drive?

C drive contains the OS and Program Files.
External D drive contains all my documents, pictures, etc.
Since D contains files that I want to back up nightly (and so does C to some extent), I need another place to put everything, which would be OneDrive.

The problem is, when putting files on OneDrive, they are also automatically placed in the OneDrive folder on C, which doesn't have enough space.

Is there a way to do backups so that everything goes to OneDrive in the cloud only?

Brink said:

Hello,

You can turn on "Files on demand" for OneDrive like below...

Mark OneDrive Files as Always keep on this device in Windows 10

....and use "Free up space" like below to have your files online-only.

Free Up Space from Locally Available OneDrive Files in Windows 10

Thanks. Yes, that's good when I can be here to babysit the computer. :)
The problem is, OneDrive mirrors all files to C, which is small, so there's no way I can do unattended backups nightly. Even if I did multiple small backups, I'd still have to manually free up space on C before the next backup begins, which is not really practical.