PSA hitting your power button (5)? times in a row (however many it takes to bring up the SOS screen) on an iPhone will disable biometric login until you’ve entered your password again.
You can also hold to power down but not actually go through with it, I believe.
That's not how it works on Android phones. Different Android phones will work differently based on the manufacturer and customization of the installed OS.
That does not encrypt your storage. It simply disables the biometric authentication methods. Which means they can see your stuff if they get into the phone via a exploit.
Fun fact: You can have two factor authentication where a PIN and a Fingerprint are required on android.
This can be done with work profiles! Set a pin for the normal phone unlock, and a biometric for the work profile. To get to any data in the work profile, someone would need both factors.
Vaguely recall reading about a way to set your phone with two PINs, your normal one, and a security one that's like a completely separate user account. So just install some BS apps on it, take some photos, and give that PIN when you need to.
A bit different, is the Duress Password from GrapheneOS:
GrapheneOS provides users with the ability to set a duress PIN/Password that will irreversibly wipe the device (along with any installed eSIMs) once entered anywhere where the device credentials are requested (on the lockscreen, along with any such prompt in the OS).
The wipe does not require a reboot and cannot be interrupted.
I am not a lawyer, always consult with a lawyer in your local jurisdiction.
I believe giving a duress password to the police, which destroys data, will definitely be a crime, destruction of evidence at the minimum. Or obstruction.
I'm all for having a duress code, I just want to be clear about the trade-offs
If they have physical access to the device, this won't help.
They can simply produce a binary copy of the (still encrypted) information inside, via specialized hardware or backdoors via the CIA / Israel, then if you given them a duress code all they lose is either the original or the copy.