First, a Word Template is not "locked down" unless you lock it down. I think you mean a locked form. Templates in Microsoft Word

Except in its intended use, a Word template is virtually indistinguishable from the document that results from use of the template. The general way a template is used is to create new documents with the same layout and resources. This can be done by double-clicking on the template or using it to form a new document from the New File Dialog.

You can use Frames (which can be a part of a paragraph Style). Frames and Textboxes in Microsoft Word

Have you examined the Cover Pages that come with Word? It sounds like you are trying to create a Cover Page.

It would also be possible to use the Advance field but I would advise looking into other options first. It is an old feature and can make editing tricky.

You should also explore use of Content Controls and editing restrictions. It would be possible to use Content Controls for the variable information for your cover page and restrict editing on most of that page while allowing it for the remainder of your template. You set exceptions where you want people able to type.

What is typed into those content controls can be repeated in headers and footers (or elsewhere) on remaining pages, if you want. One way to do this is with a StyleRef Field. Other means are explored in Repeating Data (Populating Multiple Like Fields).