If you live in a family home, you may have been disturbed by an alert on a family member's iPhone. And if that iPhone is out of your reach and no one stops it, it can get even more annoying, and if your iPhone is handy, there is a trick you can use to silence this alarm without you having to get up or call someone to stop it.
The next time you hear an alarm on a family member's iPhone and your iPhone is close and within earshot, just say “Hey Siri, turn off the alarm on the iPhone of……. ” Then say the name of the person who owns the iPhone.
Siri will ask you to confirm that you want to stop the alarm on that person's iPhone, to which you can respond with "yes" or "no," or you can tap the same two options that appear on the screen. The alarm will be silenced immediately.
Also, great about it, you can order with a nearby HomePod with Siri enabled.
Note that this feature only works if the other iPhone is owned by someone listed in the family in your Home app, it doesn't matter if they are in the iCloud family system and that person is also known in Family Sharing by the name you use to request Siri. Also, both devices must be connected to the same Wi-Fi network.