I saw some screenshots on wikia that have location labels turned on in pipboy. How do you toggle on/off?

You can either find the locations yourself, or later on in the game you can get "The Explorer" perk which enables all the locations on your map.

What? By default, the locations aren't labeled unless you mouse over them. There is an option to auto label them without having the need to mouse over. Therefore, all locations whether or not discovered, will have the name of it displayed.

Ah, well be more clear when you ask questions then! I'm not sure how to do something like that, I have always just scrolled over them. Sorry.

The pictures I've seen on the wiki are clearly photoshopped to add/have the labels visible.

Unless there's a pc GUI mod that does this, there is no 'toggle on/off' for map location names.

Sure about that? Seems like a pretty useful mod although I don't see why a single button cannot be assigned to do this. Surely someone must know for sure!

Am I sure the maps I've seen on wiki are photoshopped? Yes.
Am I sure there's no default option to turn it on/off? Yes, at least on my computer.
Am I sure there's no user-made mod that fulfills this function? No. Hence why I said "unless there's a..." ... I didn't go to Nexus to search for one. You can try doing that yourself, if you want.

PC users can use the console command tmm1, which will toggle all map markers. This also means you can fast travel straight to them without having to find them first, so is a little more useful than the Explorer perk.
Did I answer that question right or have I misinterpreted what you're asking? Happens alot with me