In order to get the android phone locked, the first step that you have to take is stopping the physical accesses to your phone. If you lose your phone and someone else finds it, stopping the physical access will not let the person go through the personal information that is inside the phone. Certain phones have programs of dual authentication. There are some android that will automatically be locked if they are not used for a long time.
If the phone is unable to connect to the home network, the matter of the phone will be erased and deleted. You may also encrypt your data to 265 as it is quite effective for classified data. You may also add a priority protocol like HAIPE or High Assurance Internet Protocol Encrypt. These are the steps that you will have to follow in order to get your Android phone locked in case it is lost or stolen.