Zoom in/out in outliner window

In the properties panel, you can zoom in/ out using: “view2d.zoom_in/out” tied to a hotkey, e.g. ctrl + or -. In the outliner, I am however unable to zoom. My UI scale is just right, but I would like to have the outliner to be just a tad smaller. Here’s what I mean, demonstrated with the properties panel:

Is there a way to do so with the outliner?