Here is a breakdown of the official specifications published on the game's PlayStation support page and Steam listing.
While the initial download might sit closer to the 90 GB mark, players must account for the decompression process that occurs during installation. Furthermore, if you opt for the (the free roguelike expansion released post-launch), you will need to account for additional gigabytes, pushing the total installation closer to 120 GB when all content is installed. God Of War Ragnarok Pc Download Size
The Valhalla DLC (the free roguelite update) is content-locked within the main game files. It does not add a separate download. The 175 GB includes Valhalla. Here is a breakdown of the official specifications
Clear space or install to a secondary drive. God Of War Ragnarok Pc Download Size