Previews or full sized images
You can save storage space by keeping previews on your local devices. On a Mac, open the Photos app and in the Photos menu, choose Settings/Preferences. In the iCloud tab, choose Optimise Mac Storage. On mobile devices, do this through Settings > [your name] > iCloud > Photos and choose Optimise [Device] Storage.
This means, for example, if you take a picture on your iPhone, it automatically appears on your iPad and Mac. Any edits you make to individual pictures or videos are