The latest firmware update comes with version number 184.108.40.206.PDMMIXM which carries a 2.4GB package size. This update Increased your system security and you can check the changelog as well as the download link.
Redmi 6 Pro v220.127.116.11.PDMMIXM changelog:
Updated Android Security Patch to September 2020. Increased system security.
If you want to check and download the latest update so follow these steps:
Tap on the smartphone Settings > System > Software update > Check for Updates Download!
Please note that before upgrading to the latest version make sure your smartphone is connected with a proper internet connection, we recommend you to download it over WIFI so that you will not face any error.