The new Apple iPhone 12 has been tested for its audio quality by DxOMark and has scored relatively well to give it a high position in the site's audio chart. However, the Xiaomi Mi 10 Pro's place at the top of the table has not been threatened, regardless of Apple's improvements over the iPhone 11's audio playback and recording.
https://www.notebookcheck.net/Xiaomi-Mi-10-Pro-remains-atop-DxOMark-audio-chart-despite-strong-showing-from-new-Apple-iPhone-12.503927.0.html