Each dragonborn's breath weapon needs a projectile that will leave behind the desired particle effect as it flies and also inflicts the desired damage type. The white dragonborn may not need this, but consistency would be preferred.

The projectile can be the Minecraft snowball for now until a new projectile is created. The sounds can also be made from vanilla Minecraft sounds. Having a working ability is more important than fancy design

The blue dragonborn needs a sound and projectile. Green and red only need a new projectile. White needs to have their effects changed to be entirely vanilla

white and blue dragonborns need new effects to apply with their breath abilities

The white and blue dragonborns now inflict slowness of different degrees and different lengths. All effects from breath weapons no longer show particles. All projectiles have been made snowballs for now. Changes still needing to be made:
-blue dragonborn particle effect for line of breath weapon
-blue and green dragonborn sounds
-red, green and white needs a custom projectile type to leave particles

Each dragonborn has had a projectile made that each leaves a trail of particles of their corresponding color. Each projectile has a fitting damage sound, and each breath ability sounds good for their element.