Hello,
I have not seen any method to “automatically” save items in a Base file. You are possibly looking at multiple items beside what you mention. There can also be macros, queries, and reports plus the form(s) and then the .odb itself.
There is the Save in Tools->Options under Load/Save->General. Have found this erratic at best especially for Base.
There are a couple of macros you can run from a toolbar for saving the .odb as a backup. Don’t believe they will save your on-going work though.
One is Any other things needed in AnnotatedBackups?.
Another can be found in the LO documentation here → LibreOffice Base Handbook. See Chapter 9 Macros → Securing you database. If recalled correctly this had an easily fixed bug in the code.
Personally don’t use any. Just hit the Save icon when needed and always have backups.
I might also add there have been numerous times I didn’t want the work saved and simply scraped the work I was doing. An automated save would need the capability to be turned on & off in this case.