Expanded Text Ads are 2x bigger than current text ads. The new ads are designed to maximize your presence and performance on mobile search results with a bigger headline and an extra long description. (And with a mobile-first mindset, whatever works on mobile is going to get applied to desktop too.)
Expanded Text ads will show across all devices – desktop and mobile – and will wrap automatically based on device size.
At this time, it isn’t possible to opt out of displaying expanded text ads. The number of ads shown in your ad units is automatically determined in order to maximize clickthroughs and revenue.