No, they are not generally overall much larger and heavier. Just look at the new lenses from Voigtländer, Leica and Zeiss for thr Leica mount. Or the Sigma 1.4/35 Art, or the 50mm Zeiss Makro-Planar / Milvus, or the Nikon 1.8/28 and 1.8/24 AF-S lenses.
Sorry, Helge is spot on. New mainstream prime lenses are, in general, huge multi-element monstrosities, and way bigger than what they replaced.
My AF-D primes are even smaller than the AF-G pictured above.




