You can create a macro to run when every document is opened (see
How to automatically execute a Word macro when you create, open, or close a document | TechRepublic
If you want the macro to only change the ribbon if one particular docx file is opened then you have two choices on how you might implement it:
1. Put the macro into a dotm template and attach that template to the docx
2. Code the macro to check the filename/path and only do anything if it matches your condition.