Can I turn off SILENCE while IPhone is locked?

Why? because your question wasn’t clear. The only Silence when Locked setting is in Do Not Disturb, and it is ignored except when Do not Disturb is enabled or scheduled.

Why did you answer a different question? Please read it if you’re going to answer bc I have the same question.

Use the switch over the Volume Buttons to mute/unmute. When it is red inside the switch, the phone is silent.