Is the default for an empty search request to return all or return none?

Hello. Is the default result for an empty search request to return all or return none? If none, is there a way to make it return all?

ie – in both the header search bar and the widget if no keywords are entered it returns no results. Is this the way it is programmed to function of is something broken? I expected it to return all.

I know this is yet another search question but have searched high and low on the forum to find out.