Thank you. I was about to add (to my original question) that I don’t even have xfce4-screensaver
installed.
I will try installing and tweaking and report back what I find.
ADDED LATER
@philm It didn’t work. I installed package, went to Screensaver Preferences, found two tabs (Screensaver and Lock Screen), and turned off the whole tab for both. Still I get screen lock.
I guess my case is the same as:
I followed some other links and saw references to a “presentation mode” as part of power management. However, my Settings > Hardware > Power Manager has no such option.