There isn't a pocket mode for this device.
Requests for features should go here:
You could contact your provider and get your code?
It should be available on your online mobile account (most providers should have this)
I would suggest only getting this replaced through official OnePlus Support or going to a service centre
So we're on Android 11 right now. Most users have found that OOS10 was stable and working well, so it shouldn't be an issue.
If you want to check...