Meta question: what's the workflow for creating PDFs like this? Is the PDF generated from markup-style text with a certain application or process?

I notice a lot of academic papers have a particular 'feel' to them, using a subset of typography styles and presentational guidelines, especially where mathematical formulae are presented to the reader.

Note: I do not have an especially academic background, nor any experience in university (tertiary) education. Please excuse my unintended ignorance on this subject. Thank you.