iPhone 13 - sometimes rings, sometimes not
Sometimes my iphone and synced apple watch ring, other times they don't.
Where notifications appear
Notifications appear on your Apple Watch or iPhone, but not both.
If your iPhone is unlocked, you'll receive notifications on your iPhone instead of your Apple Watch.
If your iPhone is locked or asleep, you'll receive notifications on your Apple Watch, unless your Apple Watch is locked.
Some apps, such as the Noise app, are only available on your Apple Watch. Notifications for these apps won't appear on your iPhone.
The red notification icon 
will appear at the top of your watch face when you have unread notifications. If you want to hide the notification icon, open the Apple Watch app on your iPhone, tap Notifications, then turn off Notifications Indicator.
When you read or dismiss notifications on your Apple Watch, they'll also be also dismissed from your iPhone.
