Size for Flyers in Marketing Content

I noticed in the Marketing Content that the default size for a flyer is A4, which is not a standard size in the US. US letter (8.5" x 11") is standard for us. Can this be added as a default size? My clients are struggling with getting the size correct as they are not graphic artists, they are realtors.

Also, is there a way to preview the Social Media reels before editing them to know exactly what they look like in action?

Thanks

James • 16m ago