When you restore an iPhone from a backup on iCloud, then the amount of time it takes depends on several variables. One of which is the total amount of data that has to be transferred and the other is the quality and speed of the Wi-Fi Network used.
Transfer Data from old iPhone to new-
Do you have a backup created either on iCloud or on your computer?
Method 1 - Backup your old iPhone on your computer like this ➔ How to back up your iPhone, iPad, and iPod touch - Apple Support and then Restore your new iPhone from that backup like this ➔Restore your iPhone, iPad, or iPod touch from a backup - Apple Support
Method 2 - The Quick Start method and here is how to do that ➔  Use Quick Start to transfer data from your previous iOS device to your new iPhone, iPad, or iPod touch - Apple Support
Axel F.