I have ColorData[1] as the default color scheme for plots in Mathematica. I would like to know what is the default color for the filling.

Please note: I understand the color is the same as the one for the line, with Opacity[0.2], but I do not want this. I want the "equivalent color" obtained by having a filling on white background.

Imagine for example you want to plot an object with Opacity[1], of the same color of the filling.

How could I do this?