Google Search Console, Google Merchant Center, Meta, Pinterest, Bing, Yandex, Baidu and Naver confirm that a store is yours by looking for a tag on its home page. Add the tag once and it appears on the home page of every storefront, on every domain, straight away.
Add a tag
In the other service, choose the HTML tag or meta tag option and copy the tag.
In Store Admin, open Online Store, then Search engines > Verification.
Paste the whole tag, or choose the service and paste only its code, then choose Add tag.
Go back to the other service and choose Verify.
The tag is on the home page while your storefront is in Maintenance or Coming Soon, or protected by a password too, so you can verify the store before it opens.
Tags added by apps
Apps you install can add their own verification tags, and each tag shows who added it. You can remove any tag; an app can remove only its own, and uninstalling an app removes its tags. Services check again from time to time, so remove a tag only when you no longer use that service. A store can have up to 20 tags.