Hello,
Headings are added to TOCs, using addHeading, embedHtml (h1 to h6 tags) a template or any other source, if the heading levels are included in the TOC. And then you need to update the TOC content.
Please check the following information about TOCs to understand how they work:
https://www.phpdocx.com/documentation/cookbook/tables-of-contents
About your question, if you extract the DOCX (it's a ZIP file), you won't file that path in the files. That information is added by some versions of MS Word by default, if you copy the file to other computer it won't appear: (https://answers.microsoft.com/en-us/mac/forum/macoffice2011-macword/hyperlinks-in-my-table-of-contents-point-to-the/ea32c870-05e6-4798-9edb-d87de6711e17?db=5)
Regards.