<?php
use Microsoft\Graph\GraphServiceClient;
use Microsoft\Graph\Generated\Users\Item\Messages\Item\Attachments\Item\AttachmentItemRequestBuilderGetRequestConfiguration;
$graphServiceClient = new GraphServiceClient($tokenRequestContext, $scopes);
$requestConfiguration = new AttachmentItemRequestBuilderGetRequestConfiguration();
$queryParameters = AttachmentItemRequestBuilderGetRequestConfiguration::createQueryParameters();
$queryParameters->expand = ["microsoft.graph.itemattachment/item"];
$requestConfiguration->queryParameters = $queryParameters;
$result = $graphServiceClient->me()->messages()->byMessageId('message-id')->attachments()->byAttachmentId('attachment-id')->get($requestConfiguration)->wait();