how can I transfer the data from iphone 8 plus to the new iPhone 14?

Where did you see any mention of a transfer data option in Settings? If you are planning to use the Quick Start method (one of the there methods described in Transfer data from your previous iOS or iPadOS device to your new iPhone or iPad - Apple Support , the option doesn't appear in Settings and it isn't available until after you have your new phone and place it beside your old phone.

See the methods described in Transfer data from your previous iOS or iPadOS device to your new iPhone or iPad - Apple Support