Nothing to do with CA itself, but rather you're talking about the docker system itself.
Can't do conditionals per se, but you can have drop downs in the template
<Config Name="Key 4" Target="VPN_PROV" Default="pia|airvpn|custom" Mode="" Description="" Type="Variable" Display="always" Required="false" Mask="false">pia</Config>
Creates a dropdown with the choice between pia, airvpn, and custom (defaults to pia)