The LG device supports three sound profiles such as Sound, Vibrate Only and Silent, and the sound profile can be changed using the normal settings, quick settings or the volume buttons.

Android 9 | LG UX 9.0
Step 1:  Open the  Settings
Step 2:  Tap on  Sound
Step 3:  Tap on  Sound profile
Step 4:  Choose between  Sound ,  Vibrate only  and  Silent
  1. Open the Settings
  2. Tap on Sound
  3. Tap on Sound profile
  4. Choose between SoundVibrate only and Silent

LG Instructions