I didn't know about this great shortcut until today. Note that it isn't particularly "silent", as it displays an "Emergency SOS" slider that, when canceled, prompts you for your password.

Apparently, saying "Hey Siri, whose phone is this?" will disable biometrics as well.

Finally, you may be interested in the "Police" shortcut[1], which sends a text to a contact, starts recording voice and video, and saves it to the cloud.

[1] https://www.icloud.com/shortcuts/2d68cb1ee7b84f08ace2fd600b9...