A warm welcome to you all. This is my first post on the forum, I hope I am not duplicating the topic.
Where in dietpi-config can I find the option to automatically start the window manager? Alternatively, if there is no such option, how do I do it by a simple method?
You mean to automatically start a desktop? Not sure what exactly you are looking for.
Yes, I mean the desktop, now the system starts in the console
Check dietpi-autostart
or have a look into our online docs System Configuration - DietPi.com Docs
And which option is responsible for this? I checked all of them and all I got was the automatic login of the selected user after use command
startx
16 or 2 should launch the desktop (if you installed one)