Unity 3D - Project Settings >> Player Settings >> Other Settings >> Auto Graphics API >> Vulkan Support

Use case - Using Vuforia within Unity-2019 ,  Packages , to create a basic "hello world" AR app .

Followed path - Unity 3D - Project Settings >> Player Settings >> XR Settings >> ...

get to see Error / Warning - "XR is currently not supported when using the Vulkan Graphics API . Please go to other settings and remove Vulkan "

As seen below choosing - Auto Graphics API - also gives an error . 

thus have deleted Vulkan from the Graphics API - and also changed the Color Space to GAMMA from LINEAR

Add the AR CAMERA - delete the MAIN CAMERA

Within INSPECTOR for the AR CAMERA - OPEN VUFORIA ENGINE CONFIGURATION .

Dont need any DATABASES within the AR CAMERA settings - None are Checked by default - So OK .

Again within the - OPEN VUFORIA ENGINE CONFIGURATION >> DEVICE TRACKER >> Track device Pose - Check this option.