Depends what it is, but the “BSD way” is that any configuration settings are in:
and those files are copied from/override settings that are listed in
i.e., /etc/defaults contains config files with every setting explicitly spelled out with its default setting specified. anything in /etc is read after /etc/defaults and thus over-rides what is set in /etc/defaults
so, either remove the specific configuration file from /etc, or hash everything out in it and you should get the defaults from /etc/defaults.
same goes for ports - they use /usr/local/etc/defaults or /usr/local/etc. as appropriate in general.
I’d recommend any FreeBSD user to have a look at the configuration files in /etc/defaults - as they can give you an idea of what configuration options CAN be set.