Question Scan/measure face length and dimensions with ARCore and AR Foundation

I am trying to create an application that allows users to scan their face, and then the app will tell them their face shapes according to the dimensions of the face.

I cannot find existing documentation that can fulfill what i require. Does anyone know where i can start? or if i have to use other libraries like OpenCV etc?

 

Checkout the documentation for AR Foundation face tracking.
https://docs.unity3d.com/Packages/com.unity.xr.arfoundation@4.2/manual/face-manager.html

You should also review the AR Foundation face mesh sample.
https://github.com/Unity-Technologies/arfoundation-samples#facemesh