A71 Camera Shutter Sound

No such option can be seen in the camera app. You need to try anyone from the following.
1) Turn ON silent mode or 'Do not disturb'.
2) Lower down the system volume while using the app.
3) Set a Bixby routine to automatically activate 'Do Not Disturb' while using camera (highly preferred).
IF >App opened>Camera,
THEN > Do not disturb.

If you haven't launched your Bixby routines app,
Goto, Settings> Advanced features> Bixby routines(switch ON and open) > Settings(from three dots) > Show Bixby routines icon. So you can get access directly from the app screen(menu).