Tap theSettingsapp to open it, then tapNotifications.
TapEmergency Alertsfor a few other options.
This is also how you stop emergency alerts from bypassing silent mode.

Got an Apple Watch?Check out how to avoid notification overload, including notifications from emergency alerts.
Can Do Not Disturb Silence Emergency and Amber Alerts on iPhone?
There is no way to block or silence Amber alerts except by turning them off.
Doing this prevents the sound from coming through your phone when you’re in silent mode.
Can You Change Emergency and Amber Alert Tones on iPhone?
These messages arrive when there is dangerous weather or another severe health or safety event imminent in your area.
EmergencyandAmber alertsgo out rarely and only in specific situations.
Given that, the disruption they cause is minor compared to the benefits they offer.
FAQ
Blue Alerts are sent out when a local law enforcement officer is injured or missing.
Like Amber Alerts, Blue Alerts are intended to help aid the community and law enforcement agencies.
To turn off iPhone notifications, go toSettings>Notifications>Show Previews>Never.
To just disable voicemail and text message alerts, disable alerts for the Phone and Messages app.
Touse emergency SOS via satellite on your iPhone, attempt to call emergency services normally.
If your phone cant connect, it will give you the satellite option.
TapEmergency Text via Satelliteand follow the on-screen prompts to establish a satellite connection.