Convert one-way to PDF

I can save a Word document as a PDF file or print it by using “Microsoft Print to PDF”.

In both cases I see that I can open the .pdf file with Word and have the original contents and edit or reuse them.

How can I save a Word document as a .pdf file so that, if not impossible, it’s almost not so easy to get the original contents in an editable way?

Is there any easy way to convert the contents to a bitmap and insert the bitmap in a .pdf file?

The same problem occurs with PowerPoint and maybe other Office applications.

Regards