He still wakes up to feed every 4 hrs stays up for 10min every feed and will sleep from 11:00pm to 11:00am and throughout the day takes 2 naps that are 2 hrs long sometimes 3hrs
If baby is waking up every 4 hours, then I don't see how they are sleeping 12 hours.
Very small babies need to be woken up to eat, but if your doctor didn't say that your baby needs this, then they can sleep as long as they wish. My kid slept through the night at this age, when earlier we were told to wake her for feeding.
It is unusual but not impossible. Strictly speaking, if the baby wakes up every four hours to eat, saying that they sleep through the night is a bit of an exaggeration, but still you are luckier than many parents.
It is worth warning that this blissful period may not last - teething, poorly sleeping while sick, not sleeping after an eventful day, nightmares, fear of darkness and other things are in the months and years to come.