Reading back a page or 2 seeing some discussion about people attempting to judge the quality of a game by its filesize, you can have a field day by comparing Mario Odyssey to just the save file size of NBA 2K18.
Never ever judge a game by its size, it tells us absolutely zero without knowing the level of compression, optimization or which focus of the game is asset heavy (music quality, are there non pre-rendered cutscenes, picture size, the way textures are handled, left over data, libraries etc.)
I just looked up how long the soundtrack for Breath of the Wild was and it is 6 hours long,
Now... Let's assume that a song of about 3 minutes at 128kbps would be 3MB, whereas in uncompressed state the same song would be 30MB. Compressed the entire soundtrack of BotW could lie anywhere between 360MB and 3,6GB. Edit: I just looked it up, it's 1,56GB.
The biggest type of data in BotW? Character models coming at
3.51GB followed by textures at
1.81GB followed by the sounds/music of
1,56GB, the 4th place goes to cutscenes at
1GB and then 5th the physics engine coming at
955MB and a finally the GUI at 6th of
620MB.
(Thanks musical_bear from Reddit who looked it up in the Extracted Wii U version) the DLC would come at
2.5GB extra data.
Tears of the Kingdom comes at 18.2 GB vs. BotW's 13.5 GB
Just to humor it let's try it out:
Totk Character models x2: 7,02GB
Removed and new textures x2: 3GB
Music is replaced and new are added: 2GB
Cutscenes replaced and x2 added: 2GB
Physics engine x2: 2GB
Basically we have a game that is 2x as large as BotW going by file size alone, I reached 16GB so far with no DLC...