How to Enable Face Unlock on the Xiaomi Redmi Note 4
While Android has a basic implementation of facial authentication, it wasn’t until the iPhone X that the feature started to gain traction. Various OEMs, including Huawei and Honor, have been working to bring their own version of the feature to their devices. Meanwhile, unofficial solutions are bringing Face ID-like unlocking to even more smartphones. XDA Junior Member shubhandu, with assistance from oc01 and Barnum on 4pda.ru, was able to port Face Unlock from the Redmi Note 5 Pro to the Xiaomi Redmi Note 4. So far, the developer has tested it on the latest Stable MIUI V188.8.131.52.NCFMIEK (MIUI9) and Developer Rom 8.2.8 (MIUI9), but a forum member says it worked for him on China Stable 184.108.40.206 as well.
The mod comes in a flashable ZIP file that you’ll have to install via TWRP (or any other compatible custom recovery). After it’s installed, you can simply boot back into Android to see the feature.