Item Modification

item.modification event is a startup script event that allows you to change properties of existing items

onEvent('item.modification', event => {
  event.modify('minecraft:ender_pearl', item => {
    item.maxStackSize = 64
    item.fireResistant = true
  })
})

All available properties:

int maxStackSize int maxDamage int burnTime String craftingReminder boolean fireResistant Rarity rarity tier = tierOptions => {

int uses float speed float attackDamageBonus int level int enchantmentValue Ingredient repairIngredient } foodProperties = food => { // note: uses functions instead of a = b

hunger(int) saturation(float) meat(boolean) alwaysEdible(boolean) fastToEat(boolean) effect(String effectId, int duration, int amplifier, float probability) removeEffect(String effectId) }