For a horizontally projectile object if the initial velocity doubled, the Vertical displacement (angle y) will be :

Answer:
Unchanged
Explanation:
horizontal projection always has initial vertical velocity equal to zero.
gravity works pretty much the same at any point on earth and will accelerate any falling object at the same rate traveling the same vertical distance in the same time. Neglecting air resistance of course.
By the way, Δy is read "delta y" not "angle y" which would be "∠ y"
delta represents a change in something, in this case the y coordinate.