Current space requirements of EA might not be indicative, however, of how big the 1.0 will be. How much space the game will require is also partially down to optimisation. If reports are correct Hitman3 (including missions from Hitman1&2) is to take less then
100 GB of space, while at this very moment Hitman2 with only two thirds of the content takes up 160GB of my drive space.
Considering the high fidelity of the game, and amount of sound clips I do expect the BG3 to be a chunky game. But how chunky I have no clue. I don't expect it to be 3x the size of early access though. I would love them to find a way to fit in 100GB. I have no clue if it's realistic or not.