I *THINK* there was an increase coming into PoP? Though, I can't even think of where to look for information on inventory-bag/bank-slot increases over Classic.
LoY was 2 Shared Bank and 8 more Bank Slots PoR was 8 more Bank Slots HoT was 2 more inventory slots CotF was 2 more Shared Bank Slots However I think they made the 2 Shared Bank slots and maybe the 8 Bank Slots from LoY part of the base game.
This spreadsheet was created for Phinigel (not by me) but it has this information plus more. It's handy to keep around.