It exists on iOS: https://support.apple.com/en-au/HT208076

Though honestly not the most obvious or accessible thing. Most people would probably just call the emergency number directly instead of using the convoluted button combination.

"You can also add emergency contacts. After an emergency call has ended, your iPhone will alert your emergency contacts with a text message, unless you choose to cancel this option. Your iPhone sends them your current location, and, for a period of time after you enter SOS mode, it sends updates to your emergency contacts when your location changes."