Users who want to mute camera app sound while taking pictures have to change the system volume slider and later turn it up. Some go a step ahead and prefer not to touch the hardware keys at all.
We could use a 3rd party solution like Slider Widget (from play store), it gives a visual control indicator what is the volume levels at that instance of usage. This was my go to app for volume control for many devices used in the past.
Those who don't want 3rd party app work around, within settings, we can use an inbuilt Accessibility feature to turn off sounds quickly in other situations as well.
Go to Settings>Accessibility>Advanced settings>Accessibility Button> Choose mute all sounds
On the navigation bar an icon for Accessibility will appear.
Interesting fact: This method is a master kill switch for sounds. When testing along with the 3rd party app Slider Widget with Accessibility icon set to mute all sounds bypasses the normal route and disables all sounds. The volume levels seen through the Slide widget remained the same. I could control the volume levels with no effect, as long as Accessibility icon has it switched off.
This was the quickest mode to mute sounds, before using the camera app, mute for in coming calls (no need to use gyro settings like flip the phone to mute), mute media sounds like when a presentation is still playing while someone is talking.
The downside : there is no visual indicator for enabled or disabled state. User will have to toggle it to check. When testing for play back of video recording, the "kill switch" disabled the sound in spite of speaker icon was toggled on. The good part of this implementation is that The "kill switch" does not disable the recording audio while video recording.
