Microsoft Windows Blog – November 6, 2017
With the Windows 10 Fall Creators Update , you can access your saved files in OneDrive just like any other file on your PC without filling up your disk space. Easily tell which files are available online only or offline. Online-only files download on demand with a double-click, and you can make them online only again to free up space – or, you can select files to always be available offline.
Source: Windows 10 Tip: Save disk space with OneDrive Files On-Demand