自作チェックボックス検索　2

まずはフォーム部分　テーマ的なとろこに

<div id="search">
<form method="get" action="<?php bloginfo( 'url' ); ?>">

 <div class="kensakutitle">講座種類</div>

    
      <?php $cats = get_categories(''); if ($cats) : ?>
    <?php foreach ( $cats as $cat ): ?>
        <div class="search-checkbox">
        <label><input type="radio" name="cat" value="<?php echo $cat->cat_ID; ?>"><?php echo esc_html( $cat->name ); ?></label>
        </div>
    <?php endforeach; ?>
    <?php endif; ?>
    
    
    
 <div class="kensakutitle">地域を選んで下さい</div>
 <div>
<?php $tags = get_tags(''); if ( $tags ) : ?>
<?php
 $checkboxes = '';
 foreach($tags as $tag) :
 $checkboxes .='<input type="checkbox" name="tag[]" value="'.$tag -> slug.'" id="tag-'.$tag->tag_id.'" /><label for="tag-'.$tag->tag_id.'">'.$tag->name.'</label>'.'&nbsp;';
 endforeach;
 print $checkboxes;
 ?>
 </div>
 <div>

 <?php endif; ?>
 <input id="submit" type="submit" value="検索" /></div>
</form>
</div>

アーカイブｐｈｐに以下をまるっとコピペ　※いらんかもしれん

<?php
/**
 * The template for displaying archive pages.
 *
 * @link https://codex.wordpress.org/Template_Hierarchy
 *
 * @package wpindex
 */

get_header(1); ?>

	<div id="primary" class="content-area">
		<main2 id="main" class="site-main" role="main">

		<?php
		if ( have_posts() ) : ?>

			<header class="page-header">
				<?php
					the_archive_title( '<h1 class="page-title">', '</h1>' );
					the_archive_description( '<div class="taxonomy-description">', '</div>' );
				?>
			</header><!-- .page-header -->

			<?php
			/* Start the Loop */
			while ( have_posts() ) : the_post();

				/*
				 * Include the Post-Format-specific template for the content.
				 * If you want to override this in a child theme, then include a file
				 * called content-___.php (where ___ is the Post Format name) and that will be used instead.
				 */
				get_template_part( 'template-parts/content', get_post_format() );

			endwhile;

			the_posts_navigation();

		else :

			get_template_part( 'template-parts/content', 'none' );

		endif; ?>

		</main><!-- #main -->
	</div><!-- #primary -->
<?php
get_sidebar();
?>
</div>
<?php

get_footer();

content.phpを以下にまるっとコピペ

<?php
/**
 * Template part for displaying posts
 *
 * @link https://developer.wordpress.org/themes/basics/template-hierarchy/
 *
 * @package index000
 */

?>

<article id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
		<header class="entry-header">
			<?php the_post_thumbnail(); ?>
		<?php
			if ( is_single() ) {
				the_title( '<h1 class="entry-title">', '</h1>' );
			} else {
				the_title( '<h2 class="entry-title"><a href="' . esc_url( get_permalink() ) . '" rel="bookmark">', '</a></h2>' );
			}

		if ( 'post' === get_post_type() ) : ?>
		<!-- .entry-meta -->
		<?php
		endif; ?>
	</header><!-- .entry-header -->


</article><!-- #post-<?php the_ID(); ?> -->

投稿数はワードプレスの管理画面→設定からでOK

チェックボックス部分を横並びはCSSに

.search-checkbox{
    display: inline-block;
}