Question: how to move all contacts from one iphone to another iphone?
Answer: Connect both of your iPhones to the Wi-Fi network > Log in the same Apple ID on your two iPhones. Go to Settings > Tap on your Apple ID's profile part > Click iCloud > Select Contacts > Tap on it to turn it on. Select Merge when it says, “What would you like to do with existing local contacts on your iPhone”.