To open a PDF file without converting it to a Word document, go to where the PDF file is stored, and open it there, without starting Word. For example, double-click the PDF file in the Documents folder on your computer or in your OneDrive.
When you're in Word and you select a PDF file to open, Word makes a copy of the PDF and converts the contents of the PDF into a format that Word can display. The original PDF is not changed at all. For more information about how this works, see Opening PDFs in Word.