To add pages to a PDF on a Mac, you can use the PDFChef for a Mac by Movavi, or you can also use the built-in Preview app.
PDFChef by Movavi
If you have a Mac, another way to add pages to a PDF is by using PDFChef for a Mac, designed by Movavi. With this software, you can open and read your PDFs, create documents, convert files from and to PDFs, for example, from and to EPUB, HTML, TXT, and Word. Most importantly, you can edit your PDFs, specifically, add pages into an existing PDF file. With this function, you can add pages, edit pages or format the texts in PDFs. Also, you can scale, rotate, and insert images on the PDF pages. To learn more about the app, follow the link below.
Learn more about PDFChef for Mac
Preview
Using Preview, users can add a blank page or a whole PDF to an existing PDF file. Specifically, you can view and save your PDFs as well as images. You can make changes to your PDFs and also edit your images.
With Preview, you can fill and sign forms on your Mac computer. You can also secure your PDF files by protecting them with a password. Also, you can change the formats of your images, from JPG to PNG, TIFF, JPEG, PSD, and vice versa. Most importantly, you can add pages to your PDF by using the Preview app. With this, you can combine and transfer pages from a PDF document to another.