Yes, Custom Types are designed for modeling pages. Content Relationship fields help you link content from one document to another. And you can add this field inside or outside Slices. I mentioned Slices because it's a good practice to think of Slices as components in your app.
So you could also select a Content relationship field at the top level of your Custom Type and then link the document you need from there. Can you tell me more details about your use case? What content do you need to showcase, do you have a visual example?