Software Update
some these new features added in the IOS 16.4 can’t be seen by my iPhone 12 don’t quite know what the problem is many features from IOS 16 don’t pop up on my device
iPhone 12, iOS 16
IOS 16 can be compatible with most devices even the iPhone 12 but running the OS doesn't guarantee that you will get those new features like battery percentage and more. Some features are excluded. iPhone age, processor can be applied here.
IOS 16 compatibility:
iOS 16 and iPadOS 16 are compatible with these devices - Apple Support
Also some features are not available in some countries:
iOS and iPadOS - Feature Availability - Apple