Well, if I understand your question, you want to know how to isolate a single polygon, yes? To do so, use the select tool (or you can select by attribute) to select your polygon you want to isolate from the greater dataset. Then, in your table of contents right-click your layer and click on "Data -> Export" Save your output as a new feature class. Use that feature class to make the highlight. Most tools in ArcGIS Pro will function only on selected items if there are any selected items in your view.
