Adding Alt Text and Title to WP Thumbnail

Question

I'm trying to modify a function to add the alt attribute and title to post thumbnails in WP.

This is the Function code:

    function dl_get_thumbnail($id, $size = 'full'){

    if (has_post_thumbnail( $id ) ){
        $image = wp_get_attachment_image_src( get_post_thumbnail_id( $id ), $size );
        $img_url = $image[0];
    } else {
        $img_url = get_stylesheet_directory_uri().'/assets/img/'.$size.'.jpg';  
    }
    
    return $img_url;
}

and this is the code output:

<?php
$class = get_post_type( get_the_ID() ) . ' col-md-4 col-sm-6 result';
?>
<article <?php post_class($class); ?>>
    <?php 
    if( get_field( 'sponsored',get_the_ID() ) ){
        echo '<span class="sponsored">Sponsored</span>';
    }
    ?>
    <div class="result_wrap">
        <header class="<?php echo get_post_type( get_the_ID() ); ?>">
            <p class="post-meta"><?php echo dl_post_meta(get_the_ID()); ?></p>
            <h2 class="entry-title"><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h2>
        </header>
            <a href="<?php echo the_permalink(); ?>"><img src="<?php echo dl_get_thumbnail(get_the_ID(),'result-large'); ?>" width="320" height="270"></a>
    </div>
</article>

What's the best way to integrate the variables into the function and then output the Alt text and Title value for the thumbnails?