Two issues -
1) Platies, swordtails and mollies do get bigger and may make better food from that perspective, but they take longer to grow to those sizes.
2) In order to breed guppies, platies or swords in the numbers needed for your purpose, the only way is to have tanks dedicated to adults/ mid size (growing fish), and other receptacles (tanks, totes, etc.) to put individual females who are just about to give birth, and which after giving birth will be immediately taken out and back into the adult colony. Then, you have tanks or totes for the small fish to grow out until your use. Otherwise, while some babies might survive in the adult colony (and some actually will), they will never be enough for the purpose intended.
This is the way variatus platies are grown as feeders for sale.
It seems as too much work unless you really want to go industrial at it....