404 Page Styling and/or Changes

For the 404 page you have a couple of options:

- If you want to use the Elementor page builder to design a 404 page, then you'd want to create a page and setup all 404s to redirect to that page. This plugin can assist with that: https://wordpress.org/plugins/404-to-301/

- Or there's also this plugin that can be used to create a custom 404 page: https://wordpress.org/plugins/404-page/