iCloud Back Up Transfer to new iPhone

If you've already setup the new phone you will need to erase it and then start over. See the instructions in Use iCloud to transfer data from your previous iOS or iPadOS device to your new iPhone, iPad, or iPod touch - Apple Support

I mean the following from step 1 in Use iCloud to transfer data from your previous iOS or iPadOS device to your new iPhone, iPad, or iPod touch - Apple Support

1 - Turn on your new device. A "Hello" screen should appear. If you've already set up your new device, you need to erase it before you can use these steps.* 

* To erase your device that's using iOS or iPadOS 15 or later, tap Settings > General > Transfer or Reset [Device] > Erase All Content and Settings. On iOS or iPadOS 14 or earlier, tap Settings > General > Reset > Erase All Content and Settings. This erases all data on your device. After you erase it, your device restarts and the "Hello" screen appears.