Here we will discuss how to change font size in PDF form on Mac, both free and paid solution included. But it's packed with poor editability, which makes it difficult to change font size, color or weight in a PDF file that contains blank form fields. PDF is now a common format for office similar to MS office, offering a smooth way to read, send and receive documents. “How do I change the font size in a PDF fillable form on a Mac?”- From Apple Discussion