Source: 9to5Google
Google Drive will now let you work with Office files, images, and PDFs in offline mode. Google started beta testing this feature back in 2019, but now it's rolling out widely to users. You will need the Google Drive for desktop app to get this work. It's available on both Mac and Windows. You also need to ensure Offline access is enabled in the Drive settings on the web. When you've set that up, right-click on a supported file to get to the "Available offline" toggle.
Another caveat is you need to have the apps to open the apps that can open these files installed on your computer. A similar feature is available on the Chrome OS Files app. If it hasn't made its way to you yet, wait for it over the coming weeks.
Source: 9to5Google