As far as I can tell the (Windows-only?) Firebird commandline options aren't documented anywhere. It would be really helpful if they could get added to, for example, the quick start guide.
For example, starting Firebird 3 as an application is firebird.exe -a
For Firebird 2.5 and earlier it is more complicated, eg fbserver.exe -a -m for SuperServer (not sure of the ones for Classic and SuperClassic).