A 3 month old baby can sleep 12 hours through the night without interruption.
Some 3 month old babies only sleep 8 hours per night while other 3 month old babies may sleep up to 12 hours which is normal.
All babies are different and some babies sleep more than other babies and there's nothing wrong with that.
Some 3 month old babies may wake up in the middle of the night and want a feeding and some may just sleep through the night.
If the baby is sleeping through the night then there's no need to wake them to feed them.
A baby will let you know when they are hungry and as long as you fed the baby before putting them to bed then they should be okay until morning.
Also if the baby is not bothered by the wet diaper or poopy diaper it's okay to let them sleep and then change the diaper when they wake up.