Can I add an "Office only" section that is only visible to the recipients of the jotform

I have seen your other threads.
https://www.jotform.com/answers/1844683 
https://www.jotform.com/answers/1844678
To avoid confusion we will assist you here.

Can I ask where do you want to add this section? Into JotForm or notification emails?
You can use hidden section collapse field to add office only section into the form.  Also, you are able to change notification email content.
Guide: How to Edit the Email Template for Notifications and Autoresponders 

Please share more information to help you. We are waiting for your answer.