KaiOS supports the screen lock feature in all versions.

You can set up your screen lock under 'Settings' -> 'Privacy & Security'

Please note that we are working with device manufacturers (OEMs) and they can chose to implement this feature or rename options in 'Settings'. If you cannot find this feature in your 'Settings' we recommend contacting your specific device manufacturer directly. 

You can find more information about our OEM partners and how to contact them here