The release date for Google's next mid-range handset has leaked, and it will be before Android 12 is expected to arrive. The Pixel 5a should, therefore, launch with Android 11.
https://www.notebookcheck.net/Google-Pixel-5a-release-date-leaks-Android-11-more-or-less-confirmed-for-mid-range-handset.548258.0.html