Open Control Center
Tap the Focus icon
Tap Do Not Disturb
Open Settings
Tap Focus
Tap Do Not Disturb
Turn on Do Not Disturb
Ask Siri to turn on Do Not Disturb
To schedule it:
Open Settings
Tap Focus
Tap Do Not Disturb
Set a schedule or automation
To allow exceptions:
Open Settings
Tap Focus
Tap Do Not Disturb
Choose allowed people or apps