A couple examples:
Fireball does 1d6/level up to 10d6. If you’re 10th level, can you cast fireball, but have it only do 1d6 damage (or 6d6 since you wouldn’t get the spell until lvl 6)
Kineticist’s Kinetic Blast. It’s basically a cantrip (but its actually a Spell-Like Ability) that does 1d6/2 levels and has an effective spell level of half your level, rounded up, max 9. So can a 10th lvl Kineticist fire a blast that only does 1d6 instead of 5d6?