How to get PDF file metadata 'Page Size' using Python?

I try to use PyPDF2 module in Python 3 but I can't display 'Page Size' property. I would like to know what the sheet of paper dimensions were before scanning to PDF file.

Something like this:

import PyPDF2
pdf=PdfFileReader("sample.pdf","rb")
print(pdf.getNumPages())

But I'm looking for another Python function instead of for example getNumPages()...

This command below prints some kind of metadata but without page size:

pdf_info=pdf.getDocumentInfo()
print(pdf_info)