Fireworks and rockets for elytra in Minecraft
Craft rockets from 1 Paper and 1 to 3 Gunpowder, open your elytra in mid-air and use a rocket:

Gunpowder is the explosive powder dropped by Creepers, and also by ghasts and witches. It is what makes TNT, firework rockets and fire charges, and it turns a potion into a splash potion.
It cannot be crafted; it can be found in chests.
Five gunpowder in a checkerboard with four sand or red sand make a TNT block. A Firework Rocket needs paper and one to three gunpowder: the more you add, the longer it flies, which also means a longer boost when you fly with elytra. Firework stars, which give rockets their colors and shapes, need gunpowder too.
In a Brewing Stand, gunpowder converts any potion into a splash potion you can throw at mobs, allies or yourself. A Fire Charge, made from gunpowder, blaze powder and coal or charcoal, is a single-use fire starter that dispensers shoot as a fireball.
Creeper farms are the classic source, since creepers drop up to two each. Gunpowder can also be found in desert temples, shipwrecks and dungeons, and the wandering trader sometimes sells it.
This item has no crafting recipe.
Craft rockets from 1 Paper and 1 to 3 Gunpowder, open your elytra in mid-air and use a rocket:
Gunpowder turns any potion into a Splash Potion with the same duration.
In a Brewing Stand fuelled with Blaze Powder, add a Fermented Spider Eye to a Water Bottle to get a Potion of Weakness (no Nether Wart needed), then add Gunpowder to…
It can be found as loot in Woodland Mansion, Desert Pyramid, Abandoned Camp and Shipwreck. It is dropped by Creeper, Ghast and Witch. Sold by Wandering Trader.
It makes TNT, firework rockets, firework stars and fire charges, and turns potions into splash potions. It is an ingredient in 4 recipes, made at the Crafting Table; for example Firework Star.