WP Hook Before a post is created

There’s a hook save_post, docs here: https://developer.wordpress.org/reference/hooks/save_post/ which will allow you to run some code after the post is saved. Example from there:

function add_user_after_post_save( $post_id ) {
     // add a user?
     // move the post to the user?
}
add_action( 'save_post', 'add_user_after_post_save' );

Not sure why you’d need to call the hook immediately before the post is created, as anything that you can do then you can also do in the save_post hook, but please provide more information.