The replies are much appreciated. I fear, however, I was clumsy in describing what I am trying to do. I will clarify.
Yes, I know that no content exists when the flow is triggered and that content is required to use the "Create new file" action. That is what I want to do in the flow, create the content in a previous action and pass it to the Create new file action.
But I don't want to just create "any" content. It is very specific. I want to create a new file that is an instance of a specific SharePoint Content Type that has a default template so that when a file is created based on that content type, it will, right out of the gate, have content.
Here is background on the SharePoint setup:
1) A SharePoint Site Content Type exists called demoCustomType:

2) That Site Content Type has a default "template" that is an Excel file. That file is already full of tabs and formulas and other content.:

3) The Site Content Type is available in a document library of a SharePoint site so that when a user selects New->demoCustomType, a NEW Excel document will be created that is effectively a "copy" of the "default template" for the demoCustomType Site Content Type:


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When a user selects New->demoCustomType, he or she will get a new file that already has the content of the default template associated with the Site Content Type.
I want to do exactly this in a Flow (create content based on a specific Site Content Type and its default template).