Many programs offer the pdf file format as an option within the “Save As” area. For example, to save an Office product (Word, Excel, PowerPoint, etc.) as a pdf, select the File menu, choose “Save As,” then select pdf from the dropdown menu. Screenshot below and walkthrough tutorial here.
You can also download many Google products (Docs, Sheets, Slides, etc.) as a pdf. Find that option in the File menu under “Download As.”
Screenshot below and walkthrough tutorial here.