Choose between the Chinese Stable ROM or a Global port (like Xiaomi.eu). Official China ROM
If you are searching for "Mi 6X firmware," you are likely looking for the MIUI-based stock firmware. However, if you own a Mi A2, flashing the Mi 6X firmware will convert your phone from Stock Android to MIUI (which many people actually prefer due to feature richness). Conversely, Mi 6X users cannot easily flash the Mi A2 Android One firmware without unlocking the bootloader and wiping data. mi 6x firmware
You need unlocked bootloader + TWRP. Then wipe System, Data, Dalvik, Cache, flash ROM + GApps (if not included) + optional Magisk for root. Choose between the Chinese Stable ROM or a