How can I set the page limit to be A4 and not exceed it? I want to write some papers and make sure that when I print the text doesn't end up scaling or anything.
You can apply A4 template to limit your writing. In desktop version of OneNote, go to "Insert" tab -> "Pages" group -> "Page Templates" button -> In "Templates" Pane -> "Add a page" -> "Blank" -> "A4" template. OneNote will create a new page with A4 page format.