I can do this via network setting's manual dns input field yet if I like to manage it via terminal (ssh), what may I do to accomplish this?
Open the file
/etc/systemd/resolved.conf in a text editor and make the desired changes. Afterwards run
sudo systemctl restart systemd-resolved to activate the changes.
Common options to change in that file are in the
[Resolve] section, for example:
Will set your dns server and search domain.
The resolved.conf manual page is a good source for information on how to edit the configuration file.