How to display subcategories on click categories page wordpress categories

Question

How to display sub categories on category page if category has subcategories else show posts of that categories wordpress category page

Answer 1

$id = $wp_query->get_queried_object_id(); // now you have the ID of the category

Now check if something is returned and do whatever from there:

$args = array('child_of' => $id);
$subcats = get_terms( $args ); 
if(!empty($subcats)){
    foreach($subcats as $subcat) {
     echo get_term_link( $subcat->slug, $subcat->taxonomy ); // for example
    }
} else {
  // do the usual stuff
}

Answer 2

You can try get_categories() with args child_of function like below.

$args = array('child_of' => 'category_id');

$categories = get_categories( $args );

foreach($categories as $category) { 
    echo '<p>Category: <a href="' . get_category_link( $category->term_id ) . '" title="' . sprintf( __( "View all posts in %s" ), $category->name ) . '" ' . '>' . $category->name.'</a> </p> ';
    echo '<p> Description:'. $category->description . '</p>';
    echo '<p> Post Count: '. $category->count . '</p>';  
}

Also, $category->count ===0 then category has no post. we can use it to check that category's post.