Way to allow client to plug in values for laid-out page

I’m looking for a way to create a page layout, styled within the theme I’m building, and then have my client be able to create new Pages with this layout. So, for instance, she will have several pages that sell widgets. I want all the widget-selling pages to have the same layout and styling. I want her to be able to upload a picture of the widget from within the editor, and have that image go where I have specified in the layout. Same with the description and links and so forth. I originally thought I was looking for a page builder, but upon playing with what I could find, it didn’t fit the bill. I want to be able to create the page layout ahead of time, and my client to simply fill in the various fields with the content of the page. Can anyone help me, either in finding such a plugin, or in directing me on what language I might use to find it myself? Thank you!