How can we upload custom page files?

WordPress is designed to use themes or plugins to output the final HTML, CSS, and JavaScript. You don’t normally directly include an HTML file, because it won’t have a way to connect to WordPress to do things like including an Elementor header or any content you can edit in the Editor.

Instead, for this type of thing, you will probably want to either create a child theme or create a plugin. Either way you can set up a PHP template that will use the HTML you want to use and allow you to pull in Editor content as well as Elementor header etc. Then you can create a page (or post, or a custom post type) in wp-admin and apply your template.

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