When porting my Godot game You're a dad to mobile I had to make UI adjustments. I didn't find any good strategies for this online, so I had to put together my own solution. I initially aimed to do something inspired by web media queries. I don't feel like I got close to that, but at least it's a workable solution.
Responsive.gdshould be autoloaded. It's the engine behind most of this.responsive_scene.gdwill be inherited by individual scene implementations. It keeps track of original values and when things should be applied.main_menu_layout.gdis an example of an inherited node.