WordPress Query order by two keys in dependency - php

Question

I sort a query by a customfield start_date (form type Ymd). The sorting should always be descending from new to old. If there are multiple entries for the date on one day, the entries should be sorted by the order of publication.
I tried it with the (post) date, ID, menu_order but it never works in all cases.
The start_date may be a different day than the post date.
Is there any query way?
Or do I have to add hours and minutes to the news_start_date field?
Or maybe switch to the post date over all, but this means in this backend flow a big lost of elegance.
$meta_query = array(
'relation' => 'AND',
array(
'key' => 'news_start_date',
'value' => $today,
'compare' => '<=',
'type' => 'DATE'
),
array(
'relation' => 'OR',
array (
'relation' => 'AND',
array(
'key' => 'news_start_date',
'value' => $expire_date,
'compare' => '>=',
'type' => 'DATE'
),
array(
'key' => 'news_end_date',
'compare' => 'NOT EXISTS'
),
),
array (
'relation' => 'AND',
array(
'key' => 'news_end_date',
'compare' => 'EXISTS'
),
array(
'key' => 'news_end_date',
'value' => $today,
'compare' => '>=',
'type' => 'DATE'
),
),
),
);
$args = array(
'post_type' => 'news',
'meta_query' => $meta_query,
'posts_per_page' => $news_count,
'meta_key' => 'news_start_date',
'orderby' => 'meta_value',
'orderby' => array(
'meta_value' => 'DESC',
'ID' => 'DESC',
//'menu_order' => 'DESC',
//'date' => 'DESC',
//'publish_date' => 'DESC',
),
'order' => 'DESC',
'post__not_in' => $sticky_posts,
'ignore_sticky_posts' => true,
'cache_results' => true,
'update_post_meta_cache' => true,
'no_found_rows' => true,
'suppress_filters' => false,
);
I tried the others fields but there was never a 100% correct order