Open Settings
Tap Notifications
Turn off Allow Notifications for each app
Turn on Focus
Tap Do Not Disturb
Schedule or enable Do Not Disturb
Turn on Silence Notifications
Turn off Time Sensitive Notifications if needed
Turn off Emergency Alerts if desired
Turn off Notification Badges
Turn off Sounds and Alerts for apps
Turn off Lock Screen notifications
Turn off Notification Center notifications
Turn off Banner notifications
Turn on Silent Mode using the Ring/Silent switch
Turn on Airplane Mode to stop all incoming alerts