The Rich Previews usually are generated in realtime by visiting your website through reading your meta tags from the HTML source of your page.

You can generate preview for each page and also in a dynamic way, for this you need:

• Define the 'url' of the website in the config / app.php file.
• Add the RichPreview component to the main layout.
• Add the preview information for each page in the tab 'meta' and 'rich preview' when you edit page (backend/cms)

if your page is a dynamic, you can override the variables:

function onEnd() {
    $this->page->meta_title       = "$var_my_title";
    $this->page->meta_description = "$var_my_description";
    $this->page->og_title         = "$var_my_title";
    $this->page->og_description   = "$var_my_description";
    $this->page->og_image         = "$var_my_link_image";
}

test the preview of your website from here