Sample Config Files
Many system daemons that come bundled in OpenBSD base have sample configuration files that you can reference in /etc/examples/. For example, suppose you want to configure a web server. Then start like so:
$ doas cp /etc/examples/httpd.conf /etc/httpd.conf
And work using that configuration file as a template.
Take a look at any README files in /usr/local/share/doc/pkg-readmes/ . Often there are special configuration instructions to get a package to work properly on OpenBSD.
You can often find your questions answered by searching through the OpenBSD mailing lists, which are conveniently archived at marc.info. These are often answered by the OpenBSD developers themselves.