You can open a locally available file anytime, even without internet access.

When you open an online-only file, it downloads to your device and becomes a locally available file. You can’t open online-only files when your device isn’t connected to the internet. You see a cloud icon for each online-only file in Finder, but the file doesn’t download to your device until you open it. Online-only files don’t take up space on your computer. Your files will have these statuses in Finder: