How to launch this Xiaomi Font Settings activity? I am trying to lauch this activity. But, can't launch.

I've tried like this.

adb shell "am start -a com.android.settings -n com.android.settings/com.android.settings.Settings$FontSettingsActivity"


Anything else I need to try?
You can try with monkey commands.

monkey -p package_name -v 500 


An alternative way is to install Nova Launcher. Run it then touch and hold an empty space in the home screen > choose Widget > Activities. Scroll down to the settings icon touch it to expend its activities then touch and hold the one you want to launch.

And from your command: adb shell "am start -a com.android.settings -n com.android.settings/com.android.settings.Settings$FontSettingsActivity" you should just put /.FontSettingsActivity after the slash.