PDFNet has built-in DOCX to PDF/XPS/XOD conversion. But does it have DOC to PDF/XPS/XOD conversion?
PDFNet does not have this functionality built-in, since there are many open-source libraries for converting DOC to DOCX. The conversion is a comparatively simple process which free tools are able to perform reliably. For example, you can find such a tool at https://code.google.com/archive/p/jodconverter/. Similarly, many free tools can reliably convert RTF or text files to DOCX.