posterizing

Install this profile and see if you like it. Posterize profile 

"Also, I'd like to outline the key features of a pic....for possible use in
making a flag using the outline."

Can you post a draft screen shot of the idea you have in mind thanks?

Using google:

https://blogs.adobe.com/jkost/2011/07/posterizing-images-with-control-and-flexibility.html

https://www.peachpit.com/articles/article.aspx?p=674693&seqNum=13

and yes, thise via PS.

I, too, originally looked under menu:/filter.

It is actually under menu:/image/adjustments.

While KR_Seals has given you good information, I'm with ManicJoe on this.

Go do it in Photoshop.

I have got some interesting results similar to posterization by pulling the curve at about the 2/3 point straight to the bottom. That will invert those tones in that part of the curve. That might be worth playing with. Try all kinds of curve manipulations, one tone at a time.

LrC does not have this feature.

While you can play with the texture and clarity sliders, your best bet it is edit in Photoshop.