In order to validate Open Graph tags please follow the link [https://developers.facebook.com/tools/debug/]. Then you need to enter the URL of the page you want to validate in a corresponding field and press the Debug button. See the example bellow:

Magento 2 Open Graph Tags Validation, Sharing Debugger

Once you have finished you'll see the page validation result. In this way, you can make sure OG tags where implemented correctly.

Magento 2 Open Graph Tags Validation, Result