Replacing 2 TB Storage Space drives with larger drives?

I have a DS5100, fully populated with 2 x 2 TB drives and 2 x 4 TB drives in a Storage Space:

(I just replaced one of the 4 TB drives because it was warning “Failure imminent”, so it’s repairing the array).

I have plenty of space available right now, but what do I do when it’s time to increase my storage? Can I replace a 2 TB drive with an 8 TB drive, repair the array, and then replace the other 2 TB drive with another 8 TB drive and repair it again? Will I have the capacity of the 8 TB drives? Or will it “repair” as if they’re only 2 TB drives?

How smart is Storage Spaces? Thanks!