How do I force the image generation to IPhone 16 dimensions/aspect ratio?

I’m trying to get it to make me some wallpaper of my dnd character. Previously, I thought it simply couldn’t make this size. But then it did. When it gave me the two option deal, it gave me the proper size. But I can’t for the life of me replicate it. The image provided is the one it made. Any idea of what prompt I can give it to make this size again? submitted by /u/Odd-Guard-2533 [link] [comments]