Add the following PHP code to your child theme functions.php file.

/*
Move email form to top of Woocommerce checkout page
*/
add_filter( 'woocommerce_billing_fields', 'custom_woo_move_checkout_email_field', 10, 1 );
 
function custom_woo_move_checkout_email_field( $address_fields ) {
    $address_fields['billing_email']['priority'] = 5;
    return $address_fields;
}