Welcome to the forum!
I don't think what your arrow points to, in your screenshot are icons. I think they are the very bottom edges of the next item in that list, above "im....3705".
Try using that vertical scroll bar on the right, to scroll the item into view.
Or you should be able to stretch that dialog longer. It's hard to notice (sometimes impossible) the bottom edge of the dialog, with the Aero themes, in Windows. But in your screenshot, I can just barely make out the bottom edge of the dialog, right under the Opacity slider, I think.
It's only the Aero themes in Windows, where this boundary sometimes can't be seen. However, I'm actually not sure if Windows 10 has any non-Aero themes. It's one of the reasons I reverted to Windows 7, after buying a new Windows 10 computer! I can't take all that bright white pretending to be transparent appearance (or whatever it's appearing to be).
Edit
Unless you mean those tiny icons in the columns to the left of your arrow? I don't think those can be made any larger. But if they can, it's with Inkscape Preferences > Interface
