As an Action, you can spread a single bag of caltrops to cover a 5-foot-square area. Any creature that enters the area must succeed on a DC 15 Dexterity saving throw or stop moving and take 1 piercing damage. Until the creature regains at least 1 hit point, its walking speed is reduced by 10 feet. A creature moving through the area at half speed doesn't need to make the saving throw.
D&D Beyond suggests that the aforementioned "bag" is 20 caltrops, which cover a five-foot square. But, what if I put 100 caltrops in a basket and had my imp familiar drop it from 100 ft in the air? Would the impact spread them over an area lager than a five-foot square without any expenditure of action economy?
If so, how would this play out? A relevant scenario might include a 15ft pinchpoint (cave entrance, portal, etc) that enemies are pouring through.
Edit for additional consideration: The idea is, PC purchases 5 bags of caltrops in town and dumps them into a basket. PC gives the basket to a flying creature, whom carries it until the encounter takes place, then ascends to Xft to drop the basket.
This is mechanically similar to spreading 5 bags of caltrops across an area, outside of initiative. However, it is more powerful because it allows players to make decisions with more information.
Do caltrop penalties stack? does not answer this question, which concerns action economy and item usage rules—not stacking penalties.