How can I add a PNG as a logo to a GameObject which can get bigger if my gameObject get bigger ? I want him to follow my GameObject dimensional changes.
Thank you for your help.
What you are looking for is a World-Space canvas
https://docs.unity3d.com/Manual/HOWTO-UIWorldSpace.html
It's a standard UI Image object in the canvas, but after setting the canvas to world space you can move, scale, rotate it by simply setting the parent of the canvas to be the gameobject in question.
There are video tutorials you can follow on the Unity site which teach you do to exactly this https://unity3d.com/learn/tutorials/topics/user-interface-ui
Here is a Live training session containing what you need https://unity3d.com/learn/tutorials/topics/multiplayer-networking/merry-fragmas-30-ui-graphics-and-animations