The commands you linked to (KP, KC, KL) are settings on the XBee that allow you (the user) to _configure_ those values which are reported to Digi Remote Manager. XBee3 Cellular devices do not have a built-in GPS or anything similar, so there is no command to retrieve physical location information (like GPS) from the XBee.
Since you say the KL command is giving you an error, you are most likely running an older XBee3 Cellular firmware. Update to the 31011 firmware which was released last month - this firmware supports the KL command.
We also added the ATAS (Active Scan) command to the 31011 firmware version. This command will let you see information about the available cells ("cell towers") in your area. https://www.digi.com/resources/documentation/digidocs/90002253/Reference/r_cmd_AS.htm