Create a custom role based on an existing role in WordPress.

example.php

<?php

if ( ! wp_roles()->is_role( 'my_customer' ) ) {
	add_role(
		'my_customer',
		__( 'My customer' ),
		array_merge(
			wp_roles()->get_role( 'customer' )->capabilities,
			array( 'read_shop_order', 'read_private_shop_orders' )
		)
	);
}