A Canadian national born in Zurich, Switzerland, McTavish helped Canada to a gold medal at the 2021 U-18 World Championship, scoring 5-6=11 points in seven tournament games while serving as the team's captain. He also represented Canada at the 2019 World Under-17 Hockey Challenge, recording 2-1=3 points in six games.
His father, Dale McTavish, played 16 seasons of professional hockey, including nine games with Calgary in 1996-97 (1-2=3 points). He spent 10 seasons in Switzerland, scoring 188-190=378 points in 361 career National League games. Dale also registered 95-60=155 points in 182 career Finnish Liiga games.