You seem to be concerned about free space. How much space does your server have?
As root user: df -h /
Used moodles only grow they don't get smaller. Can see your system is linux which is good ... means you can pursue attaching a mountable/detachable data device.
How you do that and where depends upon hosting. Example: I host some moodle servers on RackSpace and can mount a google bucket (GB) (affordable) that's 1P in size - use that mounted GB for all my site backups + course backups. Course backups are setup as a filesystem repo in Moodle so I can backup any course from any moodle site - go to another moodle site and setup file system repo that points to the same directories, and I can restore courses from other sites without having to download the backups first, only to turn around and upload ... concept - server to server.
You might check out:
https://docs.moodle.org/404/en/File_system_repository
'SoS', Ken