Add This Code In functions.php then save it.

function search_by_sku_for_admin( $search, &$query_vars ) {
    global $wpdb, $pagenow;

    if ( \'edit.php\' != $pagenow || empty($search) ) {
        return $search;
    }
    
    $args = array(
        \'posts_per_page\'  => -1,
        \'post_type\'       => \'product\',
        \'meta_query\' => array(
            array(
                \'key\' => \'_sku\',
                \'value\' => $query_vars->query[\'s\'],
                \'compare\' => \'LIKE\'
            )
        )
    );
    $posts = get_posts( $args );
    if ( empty( $posts ) ) return $search;
    $get_post_ids = array();
    foreach($posts as $post){
        $get_post_ids[] = $post->ID;
    }
    if ( sizeof( $get_post_ids ) > 0 ) {
        $search = str_replace( \'AND (((\', "AND ((({$wpdb->posts}.ID IN (" . implode( \',\', $get_post_ids ) . ")) OR (", $search);
    }
    return $search;
}
add_filter( \'posts_search\', \'search_by_sku_for_admin\', 999, 2 );