Pro Tip: Save disk space with iCloud on Mac
Save space by storing your content in iCloud or using built-in tools to find and remove large or unneeded files.
Optimized Storage helps you save storage space space by storing your content in iCloud and making it available on demand.

Store in iCloud
Click the Store in iCloud button, then choose from these options:
Desktop and Documents. Store all files from these two locations in iCloud Drive. When storage space is needed, only the files you recently opened are kept on your Mac, so that you can easily work offline. Files stored only in iCloud show a download icon , which you can double-click to download the original file. Learn more about this feature.
Photos. Store all original, full-resolution photos and videos in iCloud Photos. When storage space is needed, only space-saving (optimized) versions of photos are kept on your Mac. To download the original photo or video, just open it.
Messages. Store all messages and attachments in iCloud. When storage space is needed, only the messages and attachments you recently opened are kept on your Mac. Learn more about Messages in iCloud.
https://support.apple.com/en-us/HT206996
