Page exceprt with thumbnail

We’re working on a site for a company and trying to use Wrodpress as a CMS more then a simple blogging tool. One of the features we want is to have related content (as defined by admin) cascade across the various sections of the site. These cross links will contain an image, title, and excerpt text. Currently we have it working well for “latest posts”
https://gluepaste.com/ (Look at the bottom of the home page)
but these are posts — we need to make this work for pages but unfortunately we can’t find a tool like “WP post thumbnail” that allows us to upload image to be used for main page image and then crop and define a thumbnail version of that image.