Go to Settings > Then, scroll down and open Software update > Then, click on Download and install > If that shows that your phone's software is up-to-date then, you might need to install via Smart Switch... The better way will be that you stay on Android 11, One UI Core 3.1, Don't upgrade to Android 12, One UI Core 4.0 because in that update there are many bugs, so if you update, you may face some problems also !
