Install i3lock by entering the following commands in the terminal:
sudo apt update sudo apt install i3lock
Description:
improved screen locker
i3lock is a simple screen locker like slock. After starting it, you will see a white screen (you can configure the color/an image). You can return to your screen by entering your password. . i3lock forks so you can combine it with an alias to suspend to RAM. . You can specify either a background color or a PNG image which will be displayed while your screen is locked. . You can specify whether i3lock should bell upon a wrong password. . i3lock uses PAM and therefore is compatible with LDAP etc.
Homepage: https://i3wm.org/i3lock/
Version: 2.10-1
Section: universe/x11