Page Layout, this is on File main menu near the bottom. Use this to set the number of pages, across and down. Use Page Setup first to pick the paper size and set page size and margins. Print then save as PDF: the drawing is printed as multiple PDF pages. Export PDF, then choose: one large page pdf, or individual pdf pages, or layers as pages with a master page. Default settings: Print to PDF for multiple pages, Export PDF for one single page pdf.