How to change the language per default (nc 16.0.3)

I want to create new users, but language and country are per default in English. I need “German” (de).
My config.php (/my-nextcloud-directory/config/config.php) doesn’t offer any line for this setting.
Where can I find the correct file to change the default setting for the language?

It should be in the conf file, but all options are not present in the supplied sample file. Just simply add the line in as described in the docs

Documentation link

Thank you so much! It worked very well.:smiley: