A 7 year old boy should easily fit into Pampers Cruisers size 7 diapers or any other size 7 diapers as well as long as they are skinny enough and not overweight.
If the 7 year old is overweight or larger than some 7 year olds then they may not fit in the size 7 diapers.
I have a 7 year old who wears Pampers Cruisers size 7 diapers for bed wetting and on long car trips in case he can't make it to the bathroom in time.
The size 7 pampers cruisers fit my 7 year old son just fine and will likely fit him until he's at least 9 years old as he's pretty skinny.
He still has some room to grow into the diapers but they do fit him pretty good.
If the older kid who is wetting the bed can fit into the Pampers Cruisers size 7 diapers and they will wear the diapers then yes they can wear the Pampers Cruisers size 7 diapers for bed wetting or anytime they need too.
Some kids need to wear diapers but are still too small to fit in youth sized disposable diapers so they need to wear baby diapers or toddler diapers such as the Pampers size 7.
My son who is 7 years old fits in Pampers Cruisers size 7 diapers and wears them for bed wetting and they work great and keep him and his bed dry at night.
At first he didn't want to wear them but I finally convinced him to wear them as he used to wear Pampers diapers as a baby and toddler.
I told him though that just because he needed to wear the Pampers size 7 diapers that he wasn't a toddler or a baby and nobody else would know about it except me and his mother.
He wears clothes over the diaper so nobody knows about it and I put it on him because he has trouble getting it on properly.
Some older kids may be too big for the Pampers size 7 Cruisers diapers though but if they fit in them then they can wear them.
If not then adult diapers or youth size diapers which can be bought online would work for them.