How to design an expanded ad that converts
The image template is best if you want to get started quickly with your existing content.
The single promotion template is best for showcasing one offer or video.
The catalog template is best for promoting multiple products or offers.
Gmail Custom HTML upload : If you want to boost the trust of prospects clicking through, consider using Google’s HTML templates that you can customize fully to remain on-brand, try using video to “give viewers get a rich engagement with your brand within their email inbox, a place that they feel secure in and may view offers with less skepticism.”