From the Architecture tab of the top ribbon select the “Roof” tool drop down box and pick “Roof: Soffit”.

Ensure the correct Soffit Family is selected from the drop-down box at the top of the Properties Side Panel.

Model the Soffit.

Adjust the Soffit Pitch by selecting one of the Soffit Footprint Lines and ticking the “Define Slope” box in the top ribbon to add a pitch angle. Checking this box and entering an angle into the field next to the line adjusts pitch angle.

Adjust Soffit Elevation. This can be done in the Properties Side Panel or by moving them in an Elevation view.