Locking before suspend and hibernate can be set in LXQt Session Settings. Sometimes configuring a delay is needed when the screen is visible for a short time after resume.
Locking when idle or on laptop lid closure can be configured in Main menu → Settings → LXQt Settings → Power Management.
XScreenSaver
XScreenSaver can be configured in Main menu → Settings → Screensaver.
Other Screenlockers using Xautolock
Xautolock provides autolocking when idle and can be configured
to use any installed screenlocker. Please refer to man xautolock for more
details about possible configurations. Default timeout for idle is 10min.
A basic setup consists in adding in LXQt Session Settings under the “Autostart” section a command
like xautolock
-locker i3lock.
Another approach is defining a lock command in ~/.config/lxqt/lxqt.conf, example:
[Screensaver]
lock_command=xsecurelock