The polygon tools in the Sketch > Create panel let you create different types of polygons as sketch geometry or construction geometry in an active sketch in Fusion 360.
Circumscribed Polygon 
You click to place the center point of the polygon, specify the number of sides, then click to place the midpoint of an edge. Alternatively, you can specify a distance, then click to place a point.
Inscribed Polygon 
You click to place the center point of the polygon, specify the number of sides, then click to place a vertex point. Alternatively, you can specify a distance, then click to place a point.
Edge Polygon 
You click to place the start point and end point of one edge. Alternatively, you can place the start point, then specify the distance and angle. You specify the number of sides, then click to place a point to define the orientation of the polygon.