Ice cream: The FDA requires ice cream to contain at least 10 percent milk fat, and less than 1.4 percent egg yolk solids (more eggs create frozen custard). All frozen dairy desserts have air whipped into them, but the FDA says ice cream must weigh a minimum of 4.5 pounds per gallon — which would be close to 50% air in the product called overrun. Premium ice cream usually has less air which adds to the mouth feel and richness of the product and eating experience.
Soft serve: Soft serve generally contains 3 to 6 percent fat. Most soft serve runs at 35% air (overrun) which helps to fluff the product. This amount of overrun would come from a gravity machine where the product loads into the top of the machine called the hopper. There are pump machines which load product from the bottom and can pump higher amounts of air (overrun 60-70%).
A soft serve cone with 4 oz of actual product would look like a 5.4 oz cone by volume at 35% air/overrun. That same cone at 70% air/overrun would look like a 6.8 oz cone.
Conclusion: Bigger is not better, you are just eating more air depending on the operator’s equipment and the setting of air/overrun.
After 35 years in the business, I think 35% is the best setting on a soft serve cone.