Casting a cantrip on a higher level when multiclassing [duplicate]

Some cantrips such as ‘Thunderclap’ says in higher level(not in higher spell slot), we can give more damage.


Casting Time: 1 action Range: Self (5-foot radius) Components: S Duration: Instantaneous

You create a burst of thunderous sound, which can be heard 100 feet away. Each creature other than you within 5 feet of you must make a Constitution saving throw. On a failed save, the creature takes 1d6 thunder damage.

At Higher Levels. The spell’s damage increases by 1d6 when you reach 5th level (2d6), 11th level (3d6), and 17th level (4d6).

When we are multiclassing, does the overall level of the character effect this, or is it about the individual level of the class that is used to cast this spell?