How to have two sites with same content, diff themes running from one database

I would like to have 2 sites with identical content and different themes running from same database.

On adding a post, it should be updated on both the sites should have updated that post although with a different link.

I read older articles on this – https://wordpress.org/support/topic/two-sites-two-themes-one-database-same-content

According to the thread, it is mentioned that I have to do this –

In the second sites directory do the following:

In the wp-settings.php file change the options database value to something like this:

// Table names
$wpdb->posts = $table_prefix . 'posts';
$wpdb->users = $table_prefix . 'users';
$wpdb->categories = $table_prefix . 'categories';
$wpdb->post2cat = $table_prefix . 'post2cat';
$wpdb->comments = $table_prefix . 'comments';
$wpdb->links = $table_prefix . 'links';
$wpdb->linkcategories = $table_prefix . 'linkcategories';
$wpdb->options = 'YOURNEWPREFIX_options';
$wpdb->postmeta = $table_prefix . 'postmeta';
$wpdb->usermeta = $table_prefix . 'usermeta';

$wpdb->prefix = $table_prefix;

See how I’ve removed $table_prefix . in the options line?
Instead of YOURNEWPREFIX put something like ‘site2’ or whatever you want.

But I did not find this code in the wp-settings.php file

Please advise and help