Is it permissible to break one's fast if the fasting person slept before the Maghrib call to prayer and did not wake up until the Fajr call to prayer, knowing that the fasting period is 19 hours?

You are obligated to abstain [from food and drink], and it is forbidden for you to eat unless there is an unbearable hardship. The fast is valid if your intention is sufficient for the entire month. However, if an intention is required for each day, then the fast is not valid due to the absence of a pre-dawn intention. Scholars have differed regarding the intention for fasting Ramadan: Some believe in the necessity of a separate intention for each day, and this is the view of the Hanafis, Shafi'is, and the relied-upon position among the Hanbalis. Others have gone to the extent that a single intention suffices for the entire month, and this is the view of the Malikis and one narration from Ahmad, and it was chosen by Sheikh Ibn 'Uthaymeen. The safer approach is to make up that day.