Google seems to have removed the Trusted Places feature from Smart Lock. Many users report that the option is no longer available and users who have added Trusted Places say they are no longer working.
Trusted Places allowed users to add places where they only had to enter their passcode once, after which the phone remained unlocked at that location. This prevents people like them, for example, from having to enter their code every time. Trusted Places works based on location and not on Wi-Fi networks, for example.
Trusted Places has been a part of Smart Lock, a service provided by Google Play Services, for many years, so users need to unlock their device less often. You can do that with Body Detection, Safe Devices and Voice Match. The Familiar Face option is also available to many users. It is unknown how many users Smart Lock has. Because it is linked to Play Services, it works on any Android device with Google services.