How can I change my iPhone 13 Pro theme?

Are you referring to your iPhone’s wallpaper? If so, you can edit it by holding on your Lock Screen, continuing to swipe left until you reach the end, then tap Add and choose one of Apple’s wallpaper themes or upload your own photo. Otherwise please elaborate what theme you would like to customize.

Hello!

Which theme might you be referring to? A screenshot would be helpful if applicable.