The manual page of the
apt-key command has this:
adv Pass advanced options to gpg. With adv --recv-key you can e.g. download key from keyservers directly into the trusted set of keys.
With some searching I found the
--keyserver options but no description of what they are and no list of their friends if there are any.
If I missed the right documentation I'd be happy to be shown where to find it.