Help - Item Page Image Too Large, Possible to resize?

Novice user - Omeka Classic using Roy Theme.
Our small NPO has created a couple of Omeka Classic sites on Reclaim Hosting and we have not downloaded or installed any plugins, but we have implemented the thumbnail path in the settings. The latest site we established Rock Castle Building Interiors · Rockcastle Schools (onesharedstory.org) is using an enlarged (or zoomed) view of the uploaded image for the item page. The image is so large, only a portion of it can be seen on the web page. When you click on the oversized image, the original size image displays in its native link without the metadata framing…
I feel that the size of the image displayed on the “Item Page” is probably a setting somewhere that I just can’t find.
Can someone please advise?

The size of the generated “fullsize” image (really just a large thumbnail) is set in the Appearance → Settings panel in the admin, and that will affect the size of the image you see on the “file show” page.

We may also want to look at having the theme prevent what you’re seeing here of the image spilling past its boundaries from happening.

THANKS! I didn’t have the right vocabulary - what I really want to do is prevent the image on the Item Page from extending beyond the boundaries of the page. Is that possible?

Instead of being super-size like here: File #75: "views of st francis postcard.jpg" · Rockcastle Schools
I would be fine with the image displaying in what the software indicates is the original size https://onesharedstory.org/rockcastle/files/original/0eaa94e89676acc5d7bf684ab4da213b.jpg OR to have it confined to the boundaries of the webpage.
Is it possible to control that?