index.php

<?php get_header(); ?>
<div class="container"> 
<div class="article-list">
<?php 
$slug = (get_queried_object()) ? get_queried_object()->slug : null;
$args = array(
    'post_status' => 'publish',
    'post_type' => 'post',
    'nopaging' => true, 
);
if ( is_category() ) {
    $args['category_name'] = $slug;
} elseif ( is_tag() ) {
    $args['tag_slug__in'] = $slug;
}
$myposts = get_posts($args);

$the_year = null;
$the_month = null;
$first_year = true;
$first_month = true; 
foreach ( $myposts as $post ) : setup_postdata( $post ); ?>
    <?php
    if ( $the_year != get_the_date('Y') ) {
        $the_year = get_the_date('Y'); 
        echo '<div class="date-year-divider"><span>' . $the_year . '</span></div>';
        
        $first_year = false;
    }

    if ( get_option('showing_months_in_archive') && $the_month != get_the_date('M') ) {
        $the_month = get_the_date('M');
        echo $the_month . '<br>';
    }

    $tag_title = get_post_meta(get_the_ID(), 'meta-tag-title', true);
    $tag_color = get_post_meta(get_the_ID(), 'meta-tag-color', true);
    ?>
    <article>
        <span class="date date-month-day">
            <?=(get_option('showing_months_in_archive')) ? get_the_date('d') : get_the_date('m/d')?>
        </span>
        <?php if ( $tag_title && get_option('meta_tag_option') ) : ?>
            <span class="meta-tag-title" style="background-color: #<?=$tag_color?>"><?=$tag_title?></span>
        <?php endif; ?>
        <h3 class="archive__post-title">
            <a href="<?php the_permalink() ?>"><?=the_title();?></a>
        </h3>
        &nbsp;
        <?php if ( get_option('showing_comments_count_in_archive') ) : ?>
            <span class="archive-comment-count"><?= comments_number(0 , 1, '%') ?></span>
        <?php endif; ?>
    </article>
<?php 
endforeach; 
wp_reset_postdata();
?>
</div><!-- /.article-list -->
</div> 
<?php get_footer(); ?>