There is no cheat code for "Score x10" in any Lego Star Wars game. The cheat systems in these games unlock characters, vehicles, extras, and stud multipliers—but not a direct score multiplier.
Stud multipliers (x2 through x10) are Red Brick extras found in specific levels:
Bottom line: No cheat code exists for direct score multiplication. The x10 multiplier is a legitimate unlockable Red Brick extra. Focus on finding all Red Bricks and achieving True Jedi status for maximum scores.