Custom loot tables and fortune problem

Hello, i know it's possible to make custom loot tables with data packs, this is what i'm doing, but the question or problem i have is, i want to know how to edit how many of x material you get per fortune enchant.

Let's say i want to make a
red glazed terracotta block loot table:
Gives red coral
But, i want to edit how much red coral you're gonna get per lvl of enchant on your fortune pickaxe