Unable to display large photos

[-dp-]

I have a solution that includes student photos. The standard display is 4.5cm x 5.0cm. I would like to include a popover that displays an enlarged photo. But no matter how large I make the container, the photo remains 4.5x5.0. If I export the photo and open it in Preview, it's much larger. Any suggestions? Thanks.

macOS 10.3.6

FMA 17.0.2.205

Photos are JPGs