Chinese companies OPPO, Vivo, and Realme, are actively adding to their smartphones the function of expanding RAM. Xiaomi followed their example.
The new option will appear in the proprietary shell MIUI 13. That is, it will be available after the update. Presumably, it will work in the same way as competitors: several GB of internal memory will be used as RAM. Only in this case will you be able to add a maximum of 3 GB, which is also a lot.
According to the screenshot from the Xiaomi phone’s settings page, there will be a switch to turn this feature on or off.