Today, after doing some successful trials, I was able to create a better and much accurate parametric tapered footing in FreeCAD.
The approach was similar to the piping modeling using some sweep actions by making several planes.
The very first step was to make a parent sketch with proper constraints that would define the vertical profile of the footing.
The sketch was extruded outwards to obtain multiple planes at different heights.
Therefore, the required sketches can be produced on the obtained planes.
Then, finally making the sweeps on different sketches by defining their path from the parent sketch, the desired footing model can be obtained.