[MojaveHigh]

I use my home as a Smart Lock trusted place so that I don't have to enter my pin to unlock my phone. I could also add on-body detection.

But what if I want to quickly lock my phone? Say in the event of a robbery.

Is there a way to do that?

[can3gxw]

Hold your power key and reboot. You will be forced to enter your password when your phone restarts.

[Rocketsaucev2]

On the lock screen, hit the unlocked padlock on the bottom and the phone will be relocked

[can3gxw]

On the lock screen, hit the unlocked padlock on the bottom and the phone will be relocked

This method will "work" to lock it, but fingerprints will still unlock it. If the OP wants to make sure that he isn't forced to unlock via fingerprint - like if he is searched by police or border officials (they can force you to unlock via fingerprint or swiping but you don't have to give up the PIN or password) - then rebooting it will quickly work and you are FORCED to enter your password the first time.

[anon(847090)]

I use my home as a Smart Lock trusted place so that I don't have to enter my pin to unlock my phone. I could also add on-body detection.

But what if I want to quickly lock my phone? Say in the event of a robbery.

Is there a way to do that?

you could also use google's find my phone to lock and display message on the phone

https://www.google.com/android/devicemanager?hl=en&u=0