Question Image tracking Not working ?

If you haven't yet, you should try using the BasicImageTracking scene in the AR Foundation samples:

https://github.com/Unity-Technologies/arfoundation-samples#basicimagetracking

 

Generally speaking, AR Image Tracking only works if you use 2D images that exist in the world on 2-dimensional planes. Photographs of 3D objects will not work unless you print the photograph or render it on a 2D screen such as a computer monitor.

To answer your question more completely, some images do work better than others. Image tracking guidance is specific to your provider (ARCore, ARKit, etc), but this explanation from Apple is widely applicable across multiple platforms:

Not all images are equally suited for using them as ARReferenceImages. Good reference images typically have high contrast, good texture, clear edges, and are printed on a flat, non-glossy surface. Low-texture and low-contrast images will likely not work so well. When you add reference images to an ARResourceGroup in an Xcode asset catalog, Xcode will show quality estimation warnings, which may provide additional insights about the specific issue with that particular image.

 

ARKit allows you to capture objects in advance and then detect them at runtime: https://docs.unity3d.com/Packages/com.unity.xr.arfoundation@5.0/manual/features/object-tracking.html

There is no platform-level solution for runtime object detection on any platform, so you would be on your own to implement this or find a third-party solution. AR Foundation does not implement any AR features; it's just a cross-platform interface for features that the platforms themselves implement.