Does Open Graph help SEO?

Not directly. A good preview brings more clicks when your page is shared, and therefore more visits and links.

My new preview does not show on LinkedIn, why?

LinkedIn keeps the old preview for several days. Run the URL through its Post Inspector to force a new read.

It is better for pages that get shared often: articles, offers, tools. Otherwise, a default image with your brand is enough.

Enter an address: the tool reads the share tags of your page, checks its image and shows you the preview on Facebook, LinkedIn, X and WhatsApp.

Title and description
og:title and og:description are used as is by Facebook, LinkedIn and messaging apps. Write them to make people want to click.
A 1200 × 630 image
The 1.91:1 format shows large everywhere. Smaller or square, the image is shrunk or cropped.
The X card
twitter:card set to summary_large_image shows a large image on X. Without it, X shows a small thumbnail.
Network caches
Networks keep the preview in memory. After a fix, run your page through their inspection tool to refresh it.

Not directly. A good preview brings more clicks when your page is shared, and therefore more visits and links.
LinkedIn keeps the old preview for several days. Run the URL through its Post Inspector to force a new read.
It is better for pages that get shared often: articles, offers, tools. Otherwise, a default image with your brand is enough.

The free audit also checks mobile speed, authority, the tags of 30 pages and broken links.