new iphone will not show icloud data

If you go to Settings/Your Name, scroll to the bottom of the page, is there a Sign Out button? If so, try tapping it, and sign out. Restart and try to sign back in.

Touch ID isn't working on your iPhone or iPad.     

Try a restart.

Restart your iPhone, iPad, or iPod touch         

Try a forced restart.

Reset Device.      

If necessary

Hard reset.        

Do a backup and try a factory reset. Then restore from your backup.

Restore to Factory setting.      

Backup - Restore your device from an iCloud or iTunes backup.      

Are you using:

Set up your iPhone, iPad, or iPod touch https://support.apple.com/en-us/HT202033 or

Transfer data from your previous iOS device to your new iPhone, iPad, or iPod touch https://support.apple.com/en-us/HT201269?

I don't think you should get your result using either. Post back and explain what steps you are following when you get "iphone already added to icloud."

It sound like there already is an Apple ID on the device. Is you device activation locked, having obtained it second hand from an individual? If yes, you will need to obtain the needed password from the prior owner or have the prior owner sign out of iCloud; erase the device; and remove it from their device list. If you can do neither, then the device is useless to you.