The Schull peninsula (in Irish, An Scoil) is divided between two Catholic parishes. In one of them, Schull West, the parish records which are available online only go back to 1827, but you might still find family members there. The records are available at this link: https://registers.nli.ie/parishes/0057
The other parish, Schull East, has records going back to 1807, so if the family lived there you should be able to find even more info. Those records are available at this link:
https://registers.nli.ie/parishes/0094
There is a civil parish (an administrative district) called Skull which contains parts of both of those Catholic parishes, and there is more info about it at this link, including further links to info about the townlands within the civil parish: https://www.townlands.ie/cork/skull2/
There is a separate civil parish called Kilmoe which contains the southwesternmost parts of both of those Catholic parishes, and there is more info about it at this link, including further links to info about the townlands within that civil parish: https://www.townlands.ie/cork/kilmoe/
If you locate a baptismal record in the Catholic parish records, it will likely (though not always) state the name of the townland where the family lived, and you can then use the civil parish link above to get to info about that townland, with further links there to the 1901 and 1911 census records, as well as Griffith's Valuation (mid-1800's).