I have a scene with an animated camera fly thru. When i render the CYCLES version it shows the full screen you see in the photo (the camera viewport) when i render with EEVEE it only renders what is in the Yellow Bounding Box in the image below. How can i get EEVEE render size match the CYCLCES render size
The yellow box is the actual field of view of the camera given a specific Focal Length when using a Perspective Camera. But you have set up a Panoramic Camera - this only works in Cycles. The Material Preview uses Eevee for display, so in this mode you see the field of view of a camera with the Focal Length which is set when you switch the camera back to Perspective - which is the same Eevee will use for the finale render since it cannot render with a Panoramic Camera.
So here is a comparison. First we have the default Perspective Camera. As you can see, the field of view is the same no matter if you are in Material Preview or in Rendered View, and pretty much no difference between Cycles and Eevee.
However, if you now change the camera to a Panoramic Camera, the field of view is much different in Cycles, whereas the Material Preview and the Eevee look as they did before. That's because the Panoramic Camera only works in Cycles and is the effect is only visible in Rendered View. You can even tell Eevee will show the "normal" Perspective Camera view, because when you look at the camera settings you will see that there is a Panorama Type option in Cycles, but in Eevee (although it says Perspective for the Lens Type) you can only set a Focal Length which by default is the one you had set before.
But after all, your question was not only why it is different but how to match the field of view in Eevee to the one in Cycles. To cut it short, you cannot. The only thing you can do is use a Perspective Camera with a very very short Focal Length to widen your field of view, but it will not be the same as a Panoramic Camera. But as long as you use the Perspective Camera, the Focal Length will look the same in both Cycles and Eevee.
I've seen explanations how to create panoramic views in Eevee, but these are more like tricks involving multiple cameras etc. so you cannot simply switch from Cycles to Eevee and back and have the same field of view.