How to estimate renovated (new) house value

[Tom Matheu]

How would one estimate what the new value of a renovated / new house after it has been flipped, or torn down and rebuilt?

Let's say you buy a 1500 sq ft home on a big half acre lot in a desirable area, tear it down, and expand it to 4000 sq ft.

Would you go by sold houses price per square foot in the same area?

That seems like apples & oranges since sold comp sales may be significantly older and less desirable.