Epiphany on 6 January is not a nationwide German holiday; it applies in Baden-Württemberg, Bavaria and Saxony-Anhalt. For many calendars, it closes the Christmas school-break, carol-singing and return-travel period.
In Germany, the legal status is regional: Baden-Württemberg, Bavaria and Saxony-Anhalt treat the date as a statutory public holiday.
Public holiday in Baden-Württemberg, Bavaria and Saxony-Anhalt. The decisive place is not always the home address: workplace, school location and travel destination can each change the answer.
Check the state first. Then read school breaks, return travel, the first full January work block and any overlap with New Year's Day. That check should happen before booking travel, moving meetings or assuming that school and work calendars line up.