The simplest for you is if someone can share the patched "boot.img" (made by Magisk Manager app) for this ROM version.
But you can do it yourself if you want to try:
1) You need to find the "
boot.img" file in the
zip file of your current ROM version
2) Put this "
boot.img" file in the
root of your phone storage
3)
Install Magisk Manager app on your phone =>
https://github.com/topjohnwu/Magisk/releases/download/manager-v8.0.7/MagiskManager-v8.0.7.apk
4)
Open Magisk Manager app and tap on "
Install" button (
Magisk) => tap "
Next" (
Options) =>
Select the 2nd method
=> It will open the file manager app and you have to
find and select the "boot.img" file (
tap on the top-left menu then select "Mi 11", you should find it here)
5)
Start the install process
6)
When done, you will find "
magisk_patched_xxxxx.img" file in the '
Downloads' folder (where xxxxx = random value)
7) Transfert "
magisk_patched_xxxxx.img" file
on your computer (on your "Desktop")
8)
Reboot your device in fastboot mode (hold ' Vol - ' and ' Power ' buttons simultaneously)
9) Open a "
Command Prompt" window (
cmd) on your computer: type "
cd desktop" and then type "
fastboot flash boot magisk_patched_xxxxx.img" (
TIP: you can only type "fastboot flash boot magisk_patched" and use the TAB key to auto-complete the name, or manually replace xxxxx with correct value)
10)
When flash is done, type "
fastboot reboot"
Done! Magisk is installed!