If the child's phone is lost at home, tap “Find device” in “Quick actions” on “Home” or “Ring” in “Devices”: the phone rings loudly and vibrates even on silent. The ring can be stopped on the child's phone (in the notification) or on yours — “Stop the ring”. “Find device” is always free.
Find the device — a loud ring
Where the child is, location history, places and arrival alerts. For the adult