I had hoped that the Grammar checking would have handled this, but it does not hiccup at your sample sentence, at least not about punctuation or run-on status. It does give it a Fletch-Kincaid grade level of 17, though (i.e. grad school).

You want the macro to break it up into logical portions and decide how to punctuate it?
I'm afraid you are expecting too much from vba.

Take a look at these discussions on a macro for proper title case to get an idea of how complex ordinary English can be.

• https://www.msofficeforums.com/78192-post3.html
• Solved: How can I change text to true proper case?
• Intelligent Title Case (Microsoft Word)

That is a simple task compared to what you are contemplating.

Microsoft's new AI may handle this but do not hold your breath. I do not know that it will apply to Office 2021 anyway since it is labeled as a 365 product.

Better would be if they get the grammar checker to make suggestions. You can use the Feedback mechanism in Word to suggest this, but again, do not hold your breath.