Hey there,
You're coming from the best article related to your inquiry: Announce notifications with Siri on AirPods or Beats. "When you're wearing your AirPods or compatible Beats headphones, Siri can announce incoming notifications from apps such as Messages and Reminders, and from supported third-party apps."
-Is your iPhone 11 updated to the latest iOS 15 release? If not, please upgrade as this feature requires iPhone with iOS 15 and later: Update your iPhone, iPad, or iPod touch
1. Open the Settings app.
2. Tap Notifications.
3. Tap Announce Notifications.
4. Turn on Announce Notifications.
"Siri reads your incoming notifications out loud when your headphones are connected to your iPhone or iPad, you're wearing them, and your device is locked." Do you meet all of that criteria?
If you don’t hear Siri announcements
If you don’t hear Siri announce your notifications, try these steps:
1. Make sure that you're using a compatible device.
2. Make sure that your AirPods or your compatible Beats headphones are paired to your device in Settings > Bluetooth.
3. Go to Settings > Notifications > Announce Notifications and make sure that Announce Notifications is turned on.
4. Make sure that your iPhone or iPad is locked and its screen is dark. Siri doesn't announce messages if you're using your device.
Best regards.