<?php
use Microsoft\Graph\Beta\GraphServiceClient;
use Microsoft\Graph\Beta\Generated\Teams\Item\Channels\Item\Tabs\TabsRequestBuilderGetRequestConfiguration;
$graphServiceClient = new GraphServiceClient($tokenRequestContext, $scopes);
$requestConfiguration = new TabsRequestBuilderGetRequestConfiguration();
$queryParameters = TabsRequestBuilderGetRequestConfiguration::createQueryParameters();
$queryParameters->expand = ["teamsApp"];
$requestConfiguration->queryParameters = $queryParameters;
$result = $graphServiceClient->teams()->byTeamId('team-id')->channels()->byChannelId('channel-id')->tabs()->get($requestConfiguration)->wait();