Here are a few suggestions that don’t require conversion of PDF to another file format. One caveat is the PDF must be accessible. A scanned or inaccessible copy will not work with text-to-speech programs. Images could be problematic as some TTS programs won’t read alternative text. 

1. Adobe Read Out Loud (Built into Adobe Reader, reflow) 

2. Balabolka (Freeware – synchronous highlighting) 

3. Natural Reader (Free and paid versions, will convert to MP3) 

4. Read&Write (Software and Chrome extension, free and paid versions, dual synchronous highlighting, converts to MP3) 

5. Foxit PDF Reader (Free download, annotates)  

6. Voice Dream Reader (Paid and free app, iOS, Android, synchronous highlighting) 

7. KAMI (Paid version has TTS, annotating, highlighting)  

8. ZoomText (Paid software for low vision, TTS, magnifies text, variety of color enhancements) 

There are a few options to change the format from PDF-to-Word or PDF-to-text. I found this browser extension: https://fileconvertor.org/. Changing the visual layout of a PDF is difficult. HTML is preferable, but not always available. Magnification or text-to-speech might be the best option for someone with low vision.