That depends entirely on the theme provider. They should give you an XML file that you use to import the test data.
Or you use the theme test content. It features some edge cases, like very long category names, and all possible formatting options, like table, <pre>, nested lists, and so on.
You still need to do it, if you want to use HTML5 markup for certain elements. WordPress doesn't have any other way to tell the difference between "legacy" themes and more recent ones, and the old markup is still the default for backwards compatibility reasons. As recently as 5.3 there are still changes being made that require declaring support for html5 (...
Because the third parameter/argument in the add_meta_box function expects a callback function name, which in your case as you have supplied is homepage_meta_box_display. However you still haven't defined that function yet.
The callback function is basically used to output the meta box content, anything that you would like to show up in the metabox you are ...
Please make sure that you have handler name kirki-styles in the parent theme for the css file that you want to remove. Because wp_dequeue_style function used handler as parameter. You can check documentaion of dequeue ...