Chromatic Bolt

Make a ranged spell attack against a creature in range. On a hit, the target takes 1d6 magic damage, and a random damaging effect is applied.

At Higher Levels. When you cast this spell using a spell slot of 1st level or higher, the damage increases by 1d6, and the damaging effect is increased by 1d(effect damage) damage and last longer for each slot level above cantrip.

Increased effect length = effect length * (spell slot level +1)