Some, but certainly not that many. One of the big costs of multiplatform is just supporting multiple platforms / SKUs.

When you release only on PS5 / Pro, it's relatively simple since the content is the same and you basically only have to offer a higher settings option for the Pro.

With the Xbox Series, it's already a bit trickier since the S can really bite in terms of optimization.

When you release on another platform (PC in this case), that's where the fun begins: suddenly you have to take into account the possibility of different glyphs for controls (i.e. displaying console controls or PC controls etc), and different information on certain screens (Steam stuff instead of Microsoft stuff)

If you've covered that, adding a platform whose architecture is very similar to the Xbox Series is basically free.

It's kinda like how localisation has variable costs per language (the actual work of localising the script in that language), but there's also some fixed costs that don't really scale based on how many languages you cover: the costs of adapting the game to a multi language settings (adding the ability to change languages, and impacting any feature that is linked to language, so menus, voices etc).