I have a document with multiple sections that has a TOC at the beginning (which includes h1-h3 styles for the whole document) and I want to create a sub TOC for a single section that includes the h1-h3 styles in that section only. Is this possible without having to create new heading styles for the specific section?
If you break up the document and reassemble the parts as a Book, you can have one TOC for the book (turn on the "Include Book Documents" checkbox) and an individual TOC in any of the chapter documents (turn off "Include Book Documents").
The alternative would be to duplicate the paragraph styles in question and give them slightly different names, then use those for your secondary TOC. The duplicates would be "based on" your main styles, so would echo any changes made to them.