Yes you can run a macro to batch apply a Template to all documents in a folder. It would be safest to do this on a copy of all those documents.

The macro can refresh the styles from the template and potentially also do some other tasks if you are trying to set it up for a screen by screen output. The workflow of the macro would be:
1. Loop through all documents in a folder
2. Attach the desired template
3. Refresh styles from the template (possibly update theme colours/fonts too)
4. For each section in the document, change the page setup to legal & landscape and set the margin sizes. Possibly also set column count if also changing that.
5. Resize any graphics to new page width (if oversized)
6. Possibly export as PDF*
7. Save and Close

* I assume when you start talking about a screen size of 768x1366 that you are also converting the Word document to PDF. Is that right?

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Andrew Lockton
Chrysalis Design, Melbourne Australia