Arrowheads (and other line endings, usually referred to collectively as arrows) are a line property. Select a line and click on the Arrow Style
icon. This opens the Arrowheads menu.
There are several types of arrowheads available. Each end of the line can have a different arrowhead (or no arrowhead).
|| Arrowheads are only applicable to lines. They have no effect on an object’s border.