Can I make the burger menu trigger earlier?
If you need more flexibility, then a better option would be using the Elementor Header template. Please read the following article for more information:
If you use the Navigation Menu widget on this kind of header, it has an option to trigger the burger menu at the custom screen size:
We are constantly improving Phlox by adding new features and options and will consider some options for customizing the theme default header too, in future updates.