up grade my iphone

You cannot upgrade the storage on your phone; it will never have more than it did when you bought it. You can upgrade iCloud storage, which is used for backing up and for syncing, but it doesn’t add storage to your phone→What's the difference between device storage and iCloud storage?

Read again -> Related Article -> Upgrade to iCloud+

See also: iCloud+ plans and pricing -> iCloud+ plans and pricing - Apple Support

You don't, memory on an iPhone cannot be increased.

iCloud can, see Raicya's post.