It’s not really clear what you want to know exactly. However the Bound is an AABB (Axis Aligned Bounding Box). So it’s always aligned with either the world space (in case of Collider.bounds or Renderer.bounds) or aligned with the local space of the object (in case of Mesh.bounds). To calculate an arbitrary bounding box you would need to iterate through all vertices of the object and transform them into your desired space / orientation and calculate the bounding box there manually.

It’s not clear on what information you want to base your calculations on. In your screen shot you’ve drawn your purple line in screen space of the editor camera. So you should try to be more precise about your usecase and what you need this for.