Changing page sizes in PDF file
PdfPageEditor class in Aspose.Pdf.Facades namespace contains a property named PageSize which can be used to change the page size of an individual page or multiple pages at once. The Pages property can be used to assign the numbers of the pages on which the new page size needs to be applied. PageSize class contains a list of different page sizes as its members. Any of the members of this class can be assigned to PageSize property of the PdfPageEditor class. You can also get page size of any page using GetPageSize method and passing the page number.