How to the enlarge the font size of a journal paper I’m a low-vision person. I want to print research papers to read. But the font size is very small for me. Is there any way to make it bigger and print it?
If the paper is in PDF (the standard) you can print using the Poster option. You will need to print the page in a bigger size, to make it fit in multiple pages. 

https://helpx.adobe.com/acrobat/using/basic-pdf-printing-tasks.html

You can try to convert the PDF to word and enlarge the font before printing, but many don't convert well.

https://smallpdf.com/pt/pdf-para-word