<?php
use Microsoft\Graph\GraphServiceClient;
use Microsoft\Graph\Generated\Models\MailSearchFolder;
$graphServiceClient = new GraphServiceClient($tokenRequestContext, $scopes);
$requestBody = new MailSearchFolder();
$requestBody->setOdataType('microsoft.graph.mailSearchFolder');
$requestBody->setDisplayName('Weekly digests');
$requestBody->setIncludeNestedFolders(true);
$requestBody->setSourceFolderIds(['AQMkADYAAAIBDAAAAA==', ]);
$requestBody->setFilterQuery('contains(subject, \'weekly digest\')');
$result = $graphServiceClient->me()->mailFolders()->byMailFolderId('mailFolder-id')->childFolders()->post($requestBody)->wait();