Kashrlyyk: The 1.64 Hotfix offline backup installer of the entire game is 108 GB for me.
Sound about right. I've only downloaded the complete offline version at patch 1.03 - which is 103 GB - and every patch since, for more flexibility in terms of mod support.
The large filesize of the installers is because they also include every supported language files, which will be disregarded once the language choice is made during the install. I got 319 GB worth of Cyberpunk 2077 files in total, so a mere 58 GB doesn't sound so bad.
Okay, to be serious, the ~60 GB is because the patches also includes the langauge files, despite those not being utilized when playing the game. For that to be fixed, there would need to be individual patch files for every language, which would make the overall server storage requirements for every single game that much larger.
So instead, the storage requirements is passed down to each individual user.
There is also a case of generally poor coding with regard to how GoG patches are packed in general. I believe it was FitGirl (well-known game repacker) who made a statement on that, and she said the GoG offline solution compresses all the files twice, which ironically makes the file sizes go up. As for why GoG do that, I do not know.
If the issue is that you're short on disk space, GoG games are highly flexible if you need to get a bigger game drive. Just swap the drive for a bigger one, and just copy the games onto the new one actually works with GoG games. Steam games on the other hand, when I tried that back in the day, gave me nothing but trouble when I tried doing a simple copy-paste.
A separate, dedicated SSD for game installs has been recommended for a long time now, especially given the size of modern games.