No a breastfed baby cannot overeat and they will stop breastfeeding when there stomachs are full enough.
Just like on a baby bottle the baby will push away the nipple when they are full and no longer need feeding.
However it is possible to feed your baby too much if you try to force the baby to breastfeed or bottle feed when they are not hungry.
If the baby doesn't want to breastfeed or take the bottle then they are likely not hungry anymore and then you should wait awhile to feed them again.
Some signs that your baby may be feeding to frequently are gastric symptoms, such as tummy pains, excessive gas, greenish watery bowel movements or spitting up large amounts.
Then the baby may be getting too many feedings.