I whipped up this quick code. It has been tested and it works in my studio.
local tweeninfo = TweenInfo.new(
5,
Enum.EasingStyle.Linear,
Enum.EasingDirection.Out,
0,
false,
0
)
local tween = game:GetService("TweenService"):Create(script.Parent, tweeninfo, {CanvasSize = UDim2.new(0,0,3, 0)})
tween:Play()