Is there any way calc will save a backup copuy every few minutes (say 5)
There are settings in LibreOffice, see Help, Saving Documents Automatically
Or, you could try an extension like Timestamp Backup » Extensions which saves a timestamped copy as backup every time you save normally. This makes it easy to revert to an earlier version if things go wrong but it will fill up your hard drive.
There is no help saving docunents automatically in the latest calc in Fedora 40
[@EarnestAl deleted email address to prevent spam]
Click the links I gave.
If you don’t normally have internet access, you could install Help, see Installing LibreOffice on Linux - The Document Foundation Wiki