Schultz is Wagner's apprentice and can be found at the blacksmith near Mondstadt's main gate, wandering between different parts of the forge. His shop restocks every day. The blacksmith is named after him after Wagner lost drinking contest to him. Wagner is as honorable as he loves to drink. So when Schultz had a bottle more than he, Wagner became the master of the blacksmithy named after his apprentice.
Otherwise, Schultz is your typical man from Mondstadt. Blonde and loves a drink.