Hi @mayank_singh - there are lots of vendors now for creating PDFs, but to do it in real time you would need a PDF service available to your Campaign server that you can call via command line, API or even watched folders like Adobe Acrobat Distiller.
So for one example, you could create a watched folder in Acrobat Distiller (can be a network folder) that when you drop a Word document into, it will convert that file to PDF and apply whatever security settings you want, based on the watched folder profile. It will then save that file to the same or another folder that you pick it up from in Campaign. In your workflow you would wait for the PDF file to arrive and once its available you would continue on and send that to the recipient. Doing this in bulk might require some more complex workflows. https://helpx.adobe.com/acrobat/using/creating-pdfs-acrobat-distiller.html#about_watched_folders_acr...
This is only one option. You might look at a PDF creation API that you call in a workflow and get a secure PDF back from. You would need to see what fits your environment and needs.
PDF creation can be fairly resource intensive so if you were doing it in bulk I would probably have all the PDFs pre-created and you just import a link to the final customer PDF that you can attach or link to in the final email.