Thank you for posting the question. There is the Pega OOTB activity @baseclass.HTMLToPDF available which can be used for this purpose. On click of a button you can call a custom activity in which you can set the parameters required for the OOTB activity by using Property-Set-Stream and setting the method parameters passing your section name. Also set any other parameters required and then call the above OOTB activity.
In addition to Vijetha solution, we can include create PDF smart shape in flow. Which takes section as parameter to generate the PDF file for respective section. Please refer attached images for your reference.