How to have Binder and Outliner mirror each other's selection automatically?

I searched about this but couldn’t find the answer–the closest I got was “Binder Affects” and “Lock in place,” but they weren’t what I was looking for.

What I want, is whenever I click on a file in the binder, it’ll automatically select the same file in the outliner, and vice versa, without me having to use Ctrl+Shift+8/Real In Binder.

I don’t think that’s possible, because your Outline is just a view in one of your editors (text/Scrivenings view and corkboard being the other view options). Editors will always reflect the document you selected in the Binder to open into that editor. As far as I know, it doesn’t work back the other way.