How are Galaxy Super Clusters Generated
No, the structures are not of the size of the observable Universe. In fact modern cosmolgical models rely on the Universe being homogeneous over scales above $100 \textrm{Mpc}$. This is an observational fact, which serves as a base for the so-called cosmological principle. See also a wiki article on large-scale structure, where the scale is mentioned in the section "End of Greatness".

The scale corresponds to a few hundred million light years. The largest structures, therefore, are clearly way smaller than the size of the observable Universe, which is of order of ten billion light years.

Note, that because it takes time for the light to reach us, the current size of the Universe we observe is larger than its apparent size due to cosmological expansion.