Pampers size 7 could easily fit a skinny enough child of 7 or 8 years old so I would assume that size 8 could easily fit a 9 or 10 or even a 12 year old if they're skinny enough.
Size 7 diapers fit around 37 plus pounds and I haven't seen the size 8 diaper yet but they probably fit 40 plus pounds.
I would say size 8 diapers would easily fit a larger child or toddler that may be chubby or just bigger than normal.
I wonder what size that Pampers would come out with next?