Google Adsense added a new ad format named full-screen inline ads.
Adsense Full-screen inline ads are full-screen banner ads that appear inline with your content as a user scrolls the page.
Google said these ads appear below the fold in both Auto ads placements and responsive ad units.
How to setup In-line Ads ?
There is nothing for AdSense publishers to do to show these, Google said “if you have suitable ad placements, full-screen inline ads will automatically start to appear on your site.”
Simply If you have auto ads code in your website, the In-line ads will show automatically.
You can check Global Ads settings in Adsense to turn on or off any ad formats
Here is a GIF of the full-screen inline ads in action: