<referenceContainer name="main">
        <container name="content.top" label="Main Content Top"/>
       <container name="content" label="Main Content Area">
        <block class="MagentoFrameworkViewElementTemplate" name="test_file" template="Magento_Catalog::product/view/customProductView.phtml"/>
        </container>
        <container name="content.aside" label="Main Content Aside"/>

        <container name="content.bottom" label="Main Content Bottom"/>

    </referenceContainer>

$objectManager = MagentoFrameworkAppObjectManager::getInstance();
$storeManager = $objectManager->get('MagentoStoreModelStoreManagerInterface');
$store = $storeManager->getStore();
$mediaUrl = $store->getBaseUrl(MagentoFrameworkUrlInterface::URL_TYPE_MEDIA);