Hi @Greta33129374tamd:

Like Steve and Jeffery, I use Acrobat for this—even with FrameMaker docs which have document compare built in to the software—because of the compare controls. In Steve's screen shot the little gear icon is barely visible at the bottom, but it links to this dialog box which allows you to control what it compares in the list at the bottom:

If you haven't used Acrobat yet for Document Compare, it's definately worth exploring. 
https://helpx.adobe.com/acrobat/using/compare-documents.html

~Barb

Definitely not one of the new features of InDesign 2024.

Kasyan Servetsky has a script that can do this in a way, worth checking out: http://kasyan.ho.ua/indesign/all/compare_two_documents.html

Otherwise I use an application called Global Vision at work: https://globalvision.co/ - load the PDF original, and then PDF of the change, and it does a side-by-side comparison. Not cheap though, but definitely required for work I do.

The PDF method using Acrobat is pretty comprehensive, especially locating changes and discrepancies between documents.

I have never heard about such a functionality. I cannot even imagine how it would work. 

I've never seen that listed as a feature for the current version - InDesign 2024 (19.0).

What is your source for that information? 

It doesn't sound like a feature I have ever even heard requested for InDesign.