Two of mine were not reliably dry until well into puberty. One, like yours, was very tall for his age. I found that sizing up in Huggies Drynites was best for him. They go up to age 15 IIRC. The other used to wear a washable pull-up over his disposable, and it caught most leaks. He didn't leak every night, so only needed 3 washables. 2 would probably have been enough, but I liked to always have one available, just in case.
Things that helped (or didn't!).
Desmopressin for sleep away from home - worked for one but no effect for the other.
Lifting at 1.5-2h after lights out - ditto.
Alarm (used by the one for whom desmopressin did not work) - 1st time did not work just caused distress, 2nd year it did work but he was still not reliably dry for another couple of years.
Layering bedding: mattress protector - fitted sheet 1 - waterproof sheet 1 - fitted sheet 2 - waterproof sheet 2 - fitted sheet 3. Made life much easier when stripping beds in the middle of the night.
Antibac spray and some wipe-up cloths in the bedroom so that if you get down to the mattress protector you can just wipe it clean, dry it, and bung a fresh sheet on. Antibac anything that gets wee on it and does not go into the wash, otherwise you end up with a stinky bedroom.
Wipe-clean polyeurethane sheets. We had some of the fabric-coated ones, which are good at soaking up wee, but cannot be wiped clean and reused. Ditto with mattress protectors. We always put the fabric side down and the polyeurethane side up.
Even once ds was dry, because he was not reliably dry for several years he still had two mattress protectors on his bed: the top one was fabric up, but the bottom one was fabric down as it was the last resort. Having two protectors helped them last longer, too.
Several 4tog synthetic quilts. They fit in an ordinary washing machine and air dry fairly quickly.
It does pass!