It’s not quite two-dimensional, it’s not quite three-dimensional. It is fractal dimension.
The dimension is the power to which we raise the scale factor to get the new size. For the Menger sponge, its dimension d is the number that solves the equation 3**d=20. The number 2.7268 just about does it
I have a higher education in mathematics. Therefore, it was interesting for me to create several such mathematical NFTs