GNOME : gsettings

gsettings configurations :

GSettings — High-level API for application settings

Set the screen blank timeout settings to 30 min
Timeout for blanking the screen (seconds; 0 = never):
gsettings set org.gnome.desktop.session idle-delay 1800

Set the Screensaver lock timer
Timeout for locking the screen after blanking (seconds; 0 = instant):
gsettings set org.gnome.desktop.screensaver lock-delay 0