You've linked a model that has families which include clearance elements. That's excellent for doing clash detection. However you may not really want to see the graphics they've provided for this in all of your own documentation views.
Hopefully the clearance elements have been assigned to a unique subcategory that you can control by overriding the link's Visibility/Graphics.
If so and you'd like to control the subcategory without overriding their linked file you can use Copy to Clipboard on one of the families (TAB to select it) with the clearance elements in them. Then paste a copy somewhere in your model. Now the family's subcategories are part of your own model. You'll be able to control it via V/G without overriding the link, assuming the link is assigned to By Host.
You probably realized that doing the above is a shortcut to creating a matching subcategory assigned to the correct category in Object Styles ourselves. It is a shortcut because we probably won't know what subcategory the family is using without examining the family more closely, by opening the linked file and editing the family directly. Using Copy and then Paste provides us with a copy we can interact with directly instead and any subcategories it has are brought into our project for us.
Families are prone to inconsistency because they can be obtained from a variety of sources. Consider that even the families from Autodesk aren't entirely consistent from one to another. It may still be necessary to crack open a family to find out how their clearance elements are controlled. For example, the lines that form the "X", and the "box" around them, in this family are assigned to the Hidden Lines subcategory, not Clearance.
In 3D there are forms to indicate clearance requirements and they are assigned to a Clearance subcategory but they also have their Visible parameter unchecked which means we can't see them in the project at all, anywhere.
This family does not intend for us to turn off the clearance "X", at least not via its Clearance subcategory. It has a subcategory called clearance and the solid forms for its clearance zones are assigned it but then it was decided they shouldn't be visible at all. By the way, doing so does not prevent Revit from seeing the clearance forms when using its own Interference Checking. However in Navisworks they don't show up. That might be considered bad form (pun intended). From a family editor perspective (and user), it would have been more flexible if the Visible parameter had been associated with a Yes/No parameter to allow us to turn it on or off if necessary. Unfortunately, keeping in mind that this post began about families in a linked file, it wouldn't make any difference for us.
Consistency is easier to manage and achieve when it is your own content library and your project files. It can be a bit trickier dealing with the content that is part of the linked files you need from other disciplines. It's easy to create a family that makes me happy, or my team. It may not make the other consultants happy though. Something to think about while you're being happy making content.