Lightroom/Camera Raw: Lens profile for Nikon Z series?

If that is a Z lens then the profile is Built In. There is no, and never will be (Most Likely), a separate profile for any Z series lenses.
You can build your own if you like.

Now I am confused .... I have the latest version Lightroom Classic CC (8.2) and there is no 'Built In ' option, whatever that means .... built in to what? Cant see why this would be any differento to any other lens, Nikon or otherwise.

Many cameras have lens profiles embedded ("built-in") in the raw files by the camera.  See this help article for details: https://helpx.adobe.com/x-productkb/multi/lens-profile-support.html.   As shown in the screen shot above, the Lens Correction panel in Develop will indicate if the lens profile is built-in to the raw file. 

If you're not seeing this, select a Z 6 raw file and post screen shots of the Metadata  panel in Library and the Lens Correction panel in Develop. The Metadata panel should look like this:

Thanks to both of you (John and Just Shot Me) for leading me in the correct direction ... I was totally unaware of the 'built in' nature of profiles for some cameras... only had the Z6 for a few days.

This may be a dumb question (I don't believe in such a thing) but what if I DON'T want to apply the automatic corrections.  That is, what if I want to retain a little bit of distortion to avoid too much cropping or because I like the look, what if I want to retain some vignetting because I like the look... 

Point being, by default "Enable Profile corrections" is disabled and I can't adjust distortion and vignetting in any way.  To do so requires that I enable that option which auto-selects some random Nikon Lens with it's own profile that distorts the image based on said profile. 

I've used LR for nearly a decade shooting Canon and Nikon.  I love my Z6 but I'd like a bit more control over lens profiles and the current UX doesn't give that.

I recently (last year) tried out a few other editors because of this issue.  I was hoping the 9.2 update addressing RAW presets/defaults would address it but I wasn't to a point I could easily update my catalogs. 

That changed today....

I've yet to fully try out the RAW defaults feature.  At a minimum I'm hoping that (if at first glance I've properly understood the feature) I will avoid having to do what I've been doing since last March - applying a preset which zero's out values to avoid the garish contrast (et al) adjustments Nikon was applying in camera. 

That said, when I go to "Lens Corrections" in the Develop module the UI doesn't expose the capability to adjust the vignetting/distortion without disabling the setting as per above so I feel certain it won't be addressed by these RAW defaults. 

If CaptureOne (and I think ON1) allow me to adjust these settings without automatically applying them then why not LR?  Just give us the freedom to do so.  I know from importing some wide-angle shots into Capture One LR is definitely cropping these.

At the end of the day I can just enable manual correction, but again if I'm trying to retain a bit of distortion and say move the slider to 25% the lens selected (for example 105mm when lens used was 24-70 f/4 z) will retain distortion to that level based on the 105's profile.  I know this b/c I can switch to any other lens (say a fish-eye) on the same image and get drastically different results.  While moving the slider to 0 is effectively saying perform 0 corrections and allows me to retain all distortion this issue is keeping me from adjusting part of the way.

If I'm doing this wrong or misunderstanding what's happening let me know, but I gather from the results I've seen with my own eyes in CaptureOne that LR is restricting me with the Z lenses.

ASIDE QUESTION RE LENS PROFILES:

I recently picked up a 50 1.2 AIS.  Is there any way to quickly apply that profile to all lenses that lack one (I also have a pre-AI but AI converted 135 2.8 so I don't want to blanket apply on all images).  The current UI keeps defaulting to Nikon Cool PIX...