Lineage OS 16 is the latest version of Lineage OS which is based on Google’s Android 9.0 Pie source code. This is the successor to Lineage OS 15.1. Lineage OS was previously known as CyanogenMod which was the most used and popular Custom ROM at that time. Team Lineage OS has been doing excellent work. The Lineage OS ROMs provide a very clean and simple Pixel like user experience. The Xiaomi Mi 9 was launched in February 2019. It comes equipped with a 6.39-inch touchscreen display with a resolution of 1080×2340 pixels. The Xiaomi Mi 9 is powered by a 2.84GHz octa-core Qualcomm Snapdragon 855 processor coupled with 6GB of RAM. It packs 128GB of inbuilt storage. The Xiaomi Mi 9 runs Android 9.0 Pie at the Top of MIUI 10 out of the box. It houses a 3,300mAh battery with proprietary fast charging. It also supports wireless charging. It has all the connectivity options. It sports a 48-megapixel primary camera with an f/1.75 aperture, a secondery12-megapixel camera with an f/2.2 aperture and a third 16-megapixel camera with an f/2.2 aperture on the rear side. It sports a 20-megapixel  f/2.0 camera on the front side

Lineage OS 16 Features | Android 9.0 Pie Features

As Lineage OS 16 is based On Android 9.0 Pie’s Source code, it has all the latest Android Oreo features and in addition to that Lineage OS also has some extra customization features.

Pre-Requirements:

Make sure the bootloader on your device is unlocked and your device is rooted and you have a custom recovery installed. Make sure your device has more than 50% battery. Make sure you have taken a backup of your important data. Now proceed To Install Official Lineage OS 16 On Xiaomi Mi 9.

Downloads

Lineage OS 16 for Xiaomi Mi 9: Download Link Download GApps For Lineage OS 16 ROMs

How to Install Unofficial Lineage OS 16 On Xiaomi Mi 9 | Android 9.0 Pie

Make sure your device is rooted and have the latest TWRP recovery installed. (Check the Pre-Requirement Section Above) First, download the files from the above link. Now transfer the downloaded files to the internal storage of your device. Now reboot to the TWRP recovery by holding your power and volume down buttons together for a few seconds. Take a backup by selecting the option from the home screen and then your data and cache from the recovery menu.

Now select install and then browse for the downloaded ROM file and then select it. Next flash the Gapps file and then Magisk (optional).

Once the flashing process is completed, reboot your phone and you will be booted into Official Lineage OS 16 Based on Android Pie. If you have any doubts regarding this process, feel free to comment below. Source

How To Install Lineage OS 16 On Xiaomi Mi 9   Android 9 0 Pie - 72How To Install Lineage OS 16 On Xiaomi Mi 9   Android 9 0 Pie - 92