Answer
On his senior international debut, Serge Gnabry made a remarkable impact by scoring a hat-trick against San Marino. This impressive feat occurred in a UEFA Euro 2020 qualifying match held on November 19, 2019, where Germany faced San Marino in Serravalle. Gnabry's stellar performance contributed significantly to Germany's resounding victory over San Marino, further solidifying his status as a rising star in international football.