Porch area tells you how much material fits. It doesn't tell you how much material the house needs, and those are different questions.
A display that fills the stoop can still look undersized from the street, and the reason is almost always the building behind it.
Three things besides porch area
Facade heightA two-story elevation swallows an arrangement that would look generous on a ranch. Tall buildings need height in the display to answer them, which is why corn stalk bundles do disproportionate work on a tall house.
SetbackA house sitting 20 feet from the sidewalk is read at close range. A house at the back of a deep lot is read from farther away, and distance shrinks everything. Deep setbacks need bigger, bolder, fewer pieces; small ones survive the distance poorly.
How much wall surrounds the doorA door tucked into a narrow entry with trim close on both sides is visually contained already. A door centered in a wide expanse of siding has nothing framing it, and the display has to do that work.
The sidewalk test
Stand where people actually see the house from — the sidewalk, or the curb, or the point where a car slows down.
At that distance, can you tell there's a display? Can you tell what it's made of? A composition that resolves into a vague clump has lost.
Then walk closer and check again. The arrangement should reward the approach with detail — stems, color variation, texture — that wasn't visible from the street.
What to add when it reads small
Height first. An extra corn stalk bunch at $25 buys more visual presence than an extra bale or a handful of pumpkins. On a tall facade it's the most efficient thing available.
Then mass. An extra straw bale at $30 adds a second anchor and lets the arrangement spread without thinning.
Then pieces. Adding pumpkins to an arrangement that's already the right shape makes it denser, which helps, but it doesn't fix a scale problem on its own.
When bigger is wrong
Small houses can be overwhelmed. A cottage with a modest entry and a display sized for a manor looks like the porch is wearing something borrowed.
The tell is the door. If the arrangement has grown to the point where the entrance is no longer the thing you notice first, it's too much regardless of how the porch area worked out.
Matching tier to building, roughly
The package descriptions are written around porch size, which is the right first filter. Facade is the adjustment.
A standard front porch on a single-story house takes The Classic comfortably. The same porch on a two-story with a deep setback often wants The Manor, or The Classic plus height.
Wide entries and tall elevations are where The Manor earns its price, and estate entries with long approaches are what The Estate is built for.
When you're between tiers, the larger one is usually right — under-filling is the harder mistake to correct once the material is on the porch.