iOS 17.3 Stolen Device Protection must be manually enabled by visiting “Face ID & Passcode" under settings and it's just a slider that enables it.

Now, when I go to change my password, a pop up appears with a new experience than just asking me to enter and verity the new password for my AppleID. That new experience says "Security Delay Required to change Password” with an option to start the 1 hour timer. This does not prohibit the thief to access other apps for the next hour.