My understanding was that the Sony lenses were so big due to the high quality required for the high resolutions (e.g. 42MP A7Rii). If you were happy with less resolution or a centre crop you could build a far smaller lens...
The size is more or less a physics limitation. If you want a fast lens then your lens elements must be larger in diameter. Then you have to add more elements for correcting aberrations that are more prominent at wide aperture, thus making the lens heavier. The resolution is less of a factor, and is more dependent on things like the glasses used and manufacturing tolerances. Most of the Sony lenses are merely comparable with Canon/Nikon lenses, and behind the Sigma Art lenses unless you are comparing the G-Master series, which are more comparable with high end Zeiss glass.
My personal fave lens ever is the Fuji 35mm F1.4, which somehow manages to be really modest in size, despite being fast and razor sharp. So, it can be done.
On the other end of the spectrum, my personal fave is the Canon 200mm f2 which is a big honking chunk of glass. The portraits that that thing can do are stunning.
