You need to unlock the bootloader.
This device is unique because it runs a special "Meitu" version of MIUI. The unlocking process is the same as standard Xiaomi phones, but you will lose access to the exclusive Meitu AI beautification features and filters if you flash a custom ROM. If you just want root access on the stock ROM, proceed with caution. Unlocking the Bootloader on Xiaomi Mi CC9 Meitu Edition: The Complete Guide The Xiaomi Mi CC9 Meitu Edition is a photographer’s dream, thanks to its exclusive AI beautification algorithms. But what happens when you outgrow MIUI and want to explore custom ROMs, root access, or stock Android?