I'm new to gamedev, so decided to use a youtube tutorial to build a very basic 2D platformer. The tutorial was for 2.1, and I'm using 3.0.5, so perhaps the version is to blame. When I run the project, the scene is cropped. Thanks.
Try turning on Allow hidpi under Window in the Project Setting and see if the problem continues. If that doesn't work, try playing around with the Stretch settings.
It might be that your width and/or height is to low. Try increasing that or if you are using fullscreen you might want to turn on "Allow Hidpi" as Socrates pointed out before me.