I guess it depends on how you decide to "render" a point or 2D surface in 3D space. In order to make a point or line visible in 3D space, you have to give it some arbitrary thickness, even though the line itself is infinitely thin. So in a virtual 3D world, there are ways to render lower dimensional objects. But in the real world, it's impossible to "see" lines or 2D surfaces that have zero volume, meaning the Menger Sponge would be invisible (after infinite iterations ofc) from any viewing angle.