There is no predefined concept in PDF of text layers. PDF files don't even have to have any layers and if they do, they are not bound by any rules (at least in terms of the PDF specification) as to whether they may or may not have text within them.
If you wish to convert text as realized with fonts into filled (and/or outlined) polygons, you can do this with Acrobat Preflight's Convert Fonts to Outlines profile. This won't affect anything other than text as realized with fonts, but it will make your PDF file uneditable with the Acrobat text editing tools, incapable of being searched for text, incapable of reasonably being exported to Word or similar formats, could seriously bloat the file size, and may significantly reduce quality of print and especially display, typically making text look overly bold.
Any good reason for wanting to do this? Other than for certain sign cutting equipment, there really isn't any rendering reasons that we know of that make this a good practice?!?!?
- Dov