Just tested on my pixel:

Go to Settings

Tap on System

Select "Advanced."

Tap on "Scheduled restart."

Toggle the switch to enable it.

Choose the day and time you want your device to restart automatically.

Suppose all police would just undo that setting as soon as they got the phone.

Can’t do that when the phone is locked. If they can do that, they’re “in” and it will take them less than a day to take all data from the phone.

The point is that they don't have the passcode so they couldn't.

I have no "Advanced".

That’s why you gotta run graphene