1.12.2 Here's A Creative Solution Using Vectors on a graph

Vector arrow1Vector = p.getLocation().getDirection();
Arrow arrow1 = p.launchProjectile(Arrow.class, arrow1Vector);
if (arrow1.getVelocity().getX() < 1
&& arrow1.getVelocity().getX() > 0
&& arrow1.getVelocity().getZ() < 1
&& arrow1.getVelocity().getZ() > 0) {
arrow1.setVelocity(arrow1Vector.setZ(arrow1.getVelocity().getZ() + arrow1Distance));
arrow1.setVelocity(arrow1Vector.setX(arrow1.getVelocity().getX() - arrow1Distance));
} else if (arrow1.getVelocity().getX() < 1
&& arrow1.getVelocity().getX() > 0
&& arrow1.getVelocity().getZ() > -1
&& arrow1.getVelocity().getZ() < 0) {
arrow1.setVelocity(arrow1Vector.setZ(arrow1.getVelocity().getZ() + arrow1Distance));
arrow1.setVelocity(arrow1Vector.setX(arrow1.getVelocity().getX() + arrow1Distance));
} else if (arrow1.getVelocity().getX() > -1
&& arrow1.getVelocity().getX() < 0
&& arrow1.getVelocity().getZ() > -1
&& arrow1.getVelocity().getZ() < 0) {
arrow1.setVelocity(arrow1Vector.setZ(arrow1.getVelocity().getZ() - arrow1Distance));
arrow1.setVelocity(arrow1Vector.setX(arrow1.getVelocity().getX() + arrow1Distance));
} else if (arrow1.getVelocity().getX() > -1
&& arrow1.getVelocity().getX() < 0
&& arrow1.getVelocity().getZ() < 1
&& arrow1.getVelocity().getZ() > 0) {
arrow1.setVelocity(arrow1Vector.setZ(arrow1.getVelocity().getZ() - arrow1Distance));
arrow1.setVelocity(arrow1Vector.setX(arrow1.getVelocity().getX() - arrow1Distance));
}

using this you can launch projectiles using vectors without changing the yaw,
I know there are more simple solution i just wanted to do something more creative.