How to create a featured post with metabox - WordPress

cpt.php

<?php

# Edit your CPT $args and add the below

'register_meta_box_cb' => 'prfx_featured_meta',

funtions.php

<?php
/**
 * Adds a meta box to the post editing screen
 */
function prfx_featured_meta() {
    add_meta_box( 'prfx_meta', __( 'Featured Posts', 'prfx-textdomain' ), 'prfx_meta_callback', 'portfolio', 'normal', 'high' );
}
add_action( 'add_meta_boxes', 'prfx_featured_meta' );
 
/**
 * Outputs the content of the meta box
 */
function prfx_meta_callback( $post ) {
    wp_nonce_field( basename( __FILE__ ), 'prfx_nonce' );
    $prfx_stored_meta = get_post_meta( $post->ID );
    ?>
    <span class="prfx-row-title"><?php _e( 'Check if this is a featured post: ', 'prfx-textdomain' ); ?></span>
    <div class="prfx-row-content">
        <label for="featured-checkbox">
            <input type="checkbox" name="featured-checkbox" id="featured-checkbox" value="yes" <?php if ( isset ( $prfx_stored_meta['featured-checkbox'] ) ) checked( $prfx_stored_meta['featured-checkbox'][0], 'yes' ); ?> />
            <?php _e( 'Featured Item', 'prfx-textdomain' ); ?>
        </label>
    </div> 
  <?php
}
 
/**
 * Saves the custom meta input
 */
function prfx_meta_save( $post_id ) {
 
    // Checks save status - overcome autosave, etc.
    $is_autosave = wp_is_post_autosave( $post_id );
    $is_revision = wp_is_post_revision( $post_id );
    $is_valid_nonce = ( isset( $_POST[ 'prfx_nonce' ] ) && wp_verify_nonce( $_POST[ 'prfx_nonce' ], basename( __FILE__ ) ) ) ? 'true' : 'false';
 
    // Exits script depending on save status
    if ( $is_autosave || $is_revision || !$is_valid_nonce ) {
        return;
    }
 
  
 	// “Quick Edit” > update clears out my custom meta values
	// https://wordpress.stackexchange.com/questions/4931/quick-edit-update-clears-out-my-custom-meta-values/#answer-96055
	if (wp_verify_nonce( $_POST['_inline_edit'], 'inlineeditnonce' ) ) {	
		 return;
	} 
  
    // Checks for input and saves - save checked as yes and unchecked at no
    if( isset( $_POST[ 'featured-checkbox' ] ) ) {
        update_post_meta( $post_id, 'featured-checkbox', 'yes' );
    } else {
        update_post_meta( $post_id, 'featured-checkbox', 'no' );
    }
 
}
add_action( 'save_post', 'prfx_meta_save' );

template-page.php

<?php 
 $args = array(
  'post_type' => 'portfolio',
  'meta_query' => array(
                  array(
                  'key' => 'featured-checkbox',
                  'value' => 'yes'
          )
      )
 );
$featured_query = new WP_Query( $args ); 
?>

<?php 
	while ( $featured_query->have_posts() ) : 
	$featured_query->the_post(); 
?> 

<div class="container">
  <div class="item-image">
  <?php if ( has_post_thumbnail()) : ?>
     <a href="<?php the_permalink(); ?>" title="<?php the_title_attribute(); ?>" >
       <img src="<?php echo get_the_post_thumbnail_url( $portfolio->ID, 'full'); ?>">
     </a>
   <?php endif; ?>
  </div>
	<h2><a href="<?php the_permalink() ?>" class="package-title"><?php the_title(); ?></a></h2>
	<?php the_excerpt( 'Read More' ); ?>
	<a href="<?php the_permalink(); ?>" class="read-more">Read More...</a>
	<hr>
</div>  
<?php 
	endwhile;
?>