Use the Ring/Silent switch on the left side of the iPhone and flip it toward the back of the phone
Turn on Silent Mode in Control Center by tapping the bell icon if available
Press the volume down button until the volume is at zero
Go to Settings > Sounds & Haptics and turn off Change with Buttons if needed
Turn on Do Not Disturb or Focus mode in Control Center to silence calls and notifications
Enable Silent Mode for specific apps in each app’s notification settings if needed