I think it all depends on if they’re ready. My daughter was fully potty trained by 2.5 and I finally removed pull ups at night by 3. Given, she has had an accident or two but I think every child needs to feel what an accident feels like for it to click that they need to wake up and go. If you do this remember a waterproof bed cover!
My son was potty trained at 2, and we had him wear pull ups till I noticed he rarely had wet ones when he woke up. Once he didn’t have a lot of wet pull ups we let him wear underwear to bed a couple months later. He would occasionally have accidents but we had two pairs of sheets and two water proof sheet protectors so we would just swap out as soon as we saw he wet the bed.
Try increasing his fluids during the day and avoiding juice and milk before bed. When was he potty trained? It’s not really something you can train although if he’s still not trained by 7 I’d refer him.
2 3/4 for my daughter... the trick really was no fluids before bed
I pushed for day potty training as I didn't want nursery changing her nappies but I have let her find her own way for night time. I talked to her about it and we decided to do it around 6 months ago, she was 4.5. she will be 5 in May and I still wake her up most nights for a wee when I go to bed otherwise she wakes up around 6 to go to the toilet
Night time is body dependent when they develop, and since its not conscious its not really trainable. My oldest was 6 when she finally stopped wetting her pull-ups overnight but was day trained at 17months. My 2nd day trained at 18months and by 3 was night-time dry. My 3rd day trained by 2 (just turned 3) and wets his pull-ups at night still about 70% of the time. It's usually only after age 7 that it becomes something to talk about with a pediatrician. You get to breathe and relax and know his body will catch up when it's time. The methods to wake them from sleep to use the potty at night etc we did try a little with our 1st as we were nervous, but in the end, their sleep is just so much more important and we wish we wouldn't have.
My kid is almost 7 and still isn’t night time trained. My son’s doctors don’t seem concerned. He’s also autistic but they said even if he wasn’t they wouldn’t be concerned just yet My daughter was night time trained by 4/5 and hasn’t had an over night accident since 7 (she only had like 1-4 in a 2/3 year span) she’s 10 now
Being dry over night is hormonal, and it can take until the age of 7. My eldest was potty trained at 2 she’s now 4 and still has the odd accident in the night.