The page title for the “Blog” page can be adjusted via the settings of it, at the bottom of the page select the “Page title” tab and make changes per your needs there.
That title from the demo was created with the help of the “Section title” element that is not available in Gutenberg. So I suggest you create the blog page through the Elementor but before it, enable the possibility to edit such pages via the settings of the Elementor or rather via Dashboard -> Elementor -> Settings -> General -> enable the “Posts” post types.