Idea of Expand Icon
The Expand icon is made up of four arrows, the arrow head is a right angle and the shaft is a straight line. The arrows start around the center of an invisible square and the arrows point to a corner of the invisible square. The arrow heads each make a corner of the invisible square.
This Expand icon is made in Material Design style
developed by Google. This style is based on extremely simplified shapes, thin two-pixel lines, and is optimized for 24x24 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 6,100 icons, all in the same style and quality.