WP Show Sticky Posts First In Category Query

wp-show-sticky-posts-first-in-category.php

<?php
add_action('pre_get_posts', function($query) {
    if ($query->is_main_query() && !is_admin() && $query->is_category()) {
        $sticky_posts = get_option('sticky_posts');
        if ($sticky_posts) {
            $cat_id = get_queried_object_id();
            $sticky_query = new WP_Query([
                'post__in' => $sticky_posts,
                'cat' => $cat_id,
                'posts_per_page' => -1,
                'ignore_sticky_posts' => 1
            ]);
            $query->set('post__not_in', $sticky_posts);
            $query->set('orderby', 'date');
            add_filter('the_posts', function($posts) use ($sticky_query) {
                return array_merge($sticky_query->posts, $posts);
            });
        }
    }
});