How to make the width of the picture in the entire VKontakte post when sharing from a third-party site?

Question

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Periodically I meet reposts where the picture attached to the repost is stretched to the full width of the post. Please tell me how to do the same. Example:
grab.by/EkK6

Answer 1

Understood with pictures.
From the official docks:
But the picture must be more than 1200 pixels wide , so that it would be enlarged on the site.