God of War: Ragnarok was always going to be bigger than the 2018 reboot. However, most players probably didn't expect it to be so in a literal sense.
According to a recent report, God of War: Ragnarok will take up 90.6GB of space on the PlayStation 4. In comparison, 2018's God of War was around 45GB. This means that the sequel will be at least double its predecessor's size. PlayStation Game Size then clarified that the leaked file sizes can differ per region.
However, before you start worrying, keep in mind that this is the PS4 file size of Ragnarok. It should consume much less storage space on the PS5 thanks to its file compression technology. Although it's worth noting that Horizon: Forbidden West's PS5 version actually ended up being noticeably larger (there's a 10GB difference, give or take) than its PS4 counterpart. Also, similar to Ragnarok, Forbidden West doubled the file size of Horizon: Zero Dawn.
100GB sounds about right for Ragnarok after seeing the file sizes of exclusive titles such as Gran Turismo 7 and Forbidden West. It appears that the PS5's compression technology can only do so much for exclusives that are also available on the PS4.