The effective cutting angle on a bench plane it determined by the angle of the frog. The iron rests on the frog. The standard angle for the frog on a bench plane is 45 degrees.

With the 45 degree frog angle, a bench plane iron should be used bevel down. With the bevel down, the effective cutting angle is 45 degree. If you were to place the iron bevel up, the effective cutting angle would be increase by the bevel angle of the iron. In most cases this would increase the cutting angle to over 70 degrees, too high for planing.

On a bench plane a higher effective cutting angle can be achieved in two ways. The frog can be replaced with a high angle frog. A back bevel can be used to create a second bevel on the opposite side of the iron.