Use a canvas to lay out 2D and 3D objects. They're inserted by default as the parent of rectangles and text.
A canvas can be either in screen space, or world space:
When a canvas is in screen space, it will adapt to the size of a mobile device's screen.
To insert a canvas:
When you've selected a canvas in the Scene tab, you can make changes to it by adjusting its properties in the Inspector panel.
Uncheck this box to stop the canvas or any children from being rendered in the scene.
User the dropdown to select whether the canvas is in either:
Adjust the width and height of the canvas.
Change the position, scale or rotation.
Choose the camera or cameras on a mobile device in which you want to render the canvas and its children.