In that case, you can have a look on the following older custom ROMs based on older Android versions. Google proprietary apps are not part of many Android 11 custom ROMs. So, if you intend to run Google Play Store (obviously!), Google Maps etc. then you need to install it from external sources. The Xiaomi Stock ROM helps you downgrade

You don’t necessarily need Mi Flash Tool in order to flash fastboot ROMs on Xiaomi devices as there are pre-made scripts that you can simply run and be done with. Once that is done, you can follow steps 1-to-3 above and launch the Terminal inside the working directory (the folder where the Fastboot ROM is extracted). Finally, issue the following