Manual:$wgSkinMetaTags

Details
An array of open graph tags which should be added by all skins. Accepted values are " ", " " and " ". Since some of these fields can be provided by extensions it defaults to an empty array.

For og:image support you will need to install an extension such as.

This configuration variable only enables the output of those tags provided by MediaWiki core. Extensions can add the same tags without being affected by this setting. Use this setting only if you don't have an extension installed that already provides those meta tags.