Patddfan:
«The three apps in question are Keynote, Numbers, and Pages» came free with your «new 16" macbook pro.»
What was needed, for you to update them, was for you to “adopt” those three apps.
If you logged into the App Store (which is, often, not automatic), you should have seen a notice that you had three Apps to “adopt”.
In what way did you «delete» these three Apps?
Did you actually deinstall them?
Did you Trash the Apps in the system wide Applications Folder?
Or did you simply remove them from your Dock?
In any case, run the App Store, and Login by using the menu Store -> View My Account.
You should be prompted to login to your Apple ID (the one you use for the App Store).
If you are not immediately presented with a message about “adopting” the Apps "in question”, try going to Updates.
If still nothing, try finding those Apps and see what options you are presented with.
Since they are Free, at the very least, you should be able to “Get” them.
Please let us know if this gets this all resolved, or if there’s anything more you need.