I can successfully display the configurable product image in order detail page with the following code.
/** @var $block \Magento\Sales\Block\Order\Item\Renderer\DefaultRenderer */
$_item = $block->getItem();
$imageBuilder = $objectManager->create('\Magento\Catalog\Block\Product\ImageBuilder');
<span style="display: table-cell;"><?= $imageBuilder->setProduct($_item->getProduct())->setImageId('cart_page_product_thumbnail')->create()->toHtml(); ?></span>
But I want the image is the simple product one. Like if I buy the blue one, it shows the blue image I set in admin.
Thanks in advance.