For future reference it should be pretty easy to scale things in Godot without messing around with individual elements. Under Project Setting > Window > Display, you can change the viewport with and height to set the size of the output then scroll down to the 'Stretch' section and use the scale to adjust so things fit. I'd also recommend looking into using CanvasLayer and UI elements to anchor things like menu buttons and HUD elements on the screen if you haven't already.