You likely know that you can use Do Not Disturb on your iPhone to prevent random notifications from waking you at night or anytime you do not want to be disturbed. You can even set a Do Not Disturb schedule for your usual sleeping hours. This is great when your iPhone is locked, but what if you are reading on your iPhone and do not want to be disturbed? There is another setting in there that is important but often overlooked. You can set your iPhone to silence always instead of when it is locked. This way, you can read on your iPhone and still have Do Not Disturb on.
To prevent your iPhone from making any noise, even when it is unlocked, Open the Settings app and go to Do Not Disturb; make sure to set Silence to Always instead of While iPhone Is Locked.