<?php
use Microsoft\Graph\GraphServiceClient;
use Microsoft\Graph\Generated\Drives\Item\Items\Item\DriveItemItemRequestBuilderGetRequestConfiguration;
$graphServiceClient = new GraphServiceClient($tokenRequestContext, $scopes);
$requestConfiguration = new DriveItemItemRequestBuilderGetRequestConfiguration();
$queryParameters = DriveItemItemRequestBuilderGetRequestConfiguration::createQueryParameters();
$queryParameters->expand = ["children"];
$requestConfiguration->queryParameters = $queryParameters;
$result = $graphServiceClient->drives()->byDriveId('drive-id')->items()->byDriveItemId('driveItem-id')->get($requestConfiguration)->wait();