If you need a custom meta tag for a specific product page in Magento 2
Step 1: Go to the below-given path.
appdesignfrontendMagemonkeysCustomthemeMagento_Cataloglayoutcatalog_product_view.xml
<?xml version="1.0"?>
<page layout="1column" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
<body>
<referenceBlock name="head.additional">
<block class="MagentoCatalogBlockProductView" name="meta_type_name" template="Magento_Catalog::product/view/custom_meta_name.phtml" />
</referenceBlock>
</body>
</page>
Step 2: Create a file named custom_meta_name.phtml at the following path
appdesignfrontendMagemonkeysCustomthemeMagento_Catalogtemplatesproductview
Finally, add the below code
<meta property="og:your_custom_tag_name" content="your_custom_value" />

