Change Canvas size only in editor

Hello.

Its not really a problem and i can create my canvas well, however it has width 800 and 100 height in my editor. When i run my game its ok since i configured those % sizes on my buttons but its getting really annoyng to create more objects because of this 100 height. Is there a way to resize canvas only in editor so it will get a lttle bit easyer to create those objects ?

Thanks for the attention !