Lay Theme Forum

And last question resolved again. Here the code:

function createPostListSubCatWork() {
	global $post;
	$categories = wp_get_object_terms( $post->ID, 'category', [ 'parent' => 1, 'number' => 99 ] );
    $categoryOutput = [];

    if (!empty($categories)) {
        array_push($categoryOutput, '<ul class="_Default">');
        foreach($categories as $category) {
            array_push($categoryOutput, '<a href="' . get_category_link( $category->term_id ) . '" title="' . sprintf( __( "View all posts in %s" ), $category->name ) . '" ' . '>' . $category->name.'</a> </br> ');
        }
        array_push($categoryOutput, '</ul>');
    }

    return implode('', $categoryOutput);
}
add_shortcode('work_cats_pg', 'createPostListSubCatWork');

• List categories for the current post: [work_cats_pg]
• The categories should be children of category 1.
• No more than 99 positions should be displayed.

Source which kinde resolved it for me: https://wordpress.stackexchange.com/questions/330128/display-a-list-of-subcategories-from-specific-category-a-post-belongs-to

Best regards,
Amadezs

Awesome! Thank you very much :)