Xiaomi Android Update Policy
Xiaomi doesn't list their official polciy on their website, but according to several reliable sources, they do have a company-wide policy on how Android updates work for each model.
Here's the basics for each model category and their Android updates:
|Xiaomi Mi series||2 major Android updates|
|Xiaomi Redmi K series||2 major Android updates|
|Xiaomi Redmi Note series||1 major Android update|
|Other Xiaomi Redmi models||1 major Android update|
|Xiaomi POCO F series||2 major Android updates|
|Xiaomi POCO X series||2 major Android updates|
|Xiaomi POCO M series||1 major Android update|
|Xiaomi POCO C series||1 major Android update|
Please note that the updates are counted after the phone was first time released. This means that if the phone was released with Android 11 and its update policy promises 2 major updates, it will receive Android 12 and Android 13. However, you might buy the phone later - say, after it has already received Android 12 update. In that case, your phone will get only the Android 13 update. So, the updates are counted from the release date onwards, not from the purchase date.
Bear in mind that this policy is unofficial and can be change at any time. But it gives a good indication on how well each Xiaomi model supported.