OnePlus
Enable or Disable Screen Lock Sound auf OnePlus
Locking your OnePlus with the power button triggers a short click tone by default. This sound comes from the general system sound package, not from notification or focus profiles, so muting your ringer alone does not remove it.
To change it, open Settings ➔ tap on Sounds & vibration ➔ tap on System sounds ➔ enable or disable Screen locking sounds. The toggle applies right away, so you can lock the screen immediately after to check the result.
Turning this off does not affect other system sounds such as touch tones or keyboard clicks - those sit as separate switches on the same screen. If you rely on Do Not Disturb or a scheduled Focus profile, the lock sound still plays independently, since it belongs to system sounds rather than notification behavior.
If you flip the toggle on but still hear nothing, check that media volume is not muted. Screen locking sounds route through that same audio channel on most OnePlus devices.