I’ve known about this feature baked into the iPhone 14 (and 14 Pro/Max) models but heard this story from the Lahaina (Maui) files that cements the true value of this technology.  To summarize, the SOS features is a combination of hardware and software that couples with a partnership with Globalstar’s 24 low orbit satellites.  It can establish a signal using these satellites to get an emergency message when you have no cellular service using voice or text messaging.

For one family surrounded by flames in the Lahaina fire with no cellular service they were able to connect with a dispatcher who sent a fire unit to their exact location and they are alive today because of it. You can read that store here:
https://www.macworld.com/article/2027967/iphone-14-emergency-sos-via-satellite-hawaii-maui-wildfires.html

The feature (like the Crash Detection function in iPhone 14 or higher) will alert your chosen family or friends to your situation.
Make sure to set up your Emergency Contacts in your iPhone to take advantage of this feature.  You can read about this SOS function via this Apple Support article: https://support.apple.com/en-us/HT213426

NOTE: We are advised NOT to use this service without an actual emergency - but there is a Demo function available (in this same Apple Support article) that you can use to better understand and practice this service.