If you need to use brand newiPhoneInitialization, new iPhones and old iPhones must all run iOS 12.4 or newer systems. The new iPhones after the end of August will basically be iOS 12.4 systems.
If you have two iPhones that are compatible with this feature, just put the new iPhone on the side of the old iPhone, confirm the Apple ID and start typing. You need to enter the old iPhone's lock screen password on the new iPhone.
Once the initialization is complete, you can choose iCloud or a new direct transfer. Direct transfer bypasses iCloud, and all photos, media, app data, and settings are transmitted wirelessly. However, apps are downloaded through the App Store, which means networking is required. The transmission time will vary depending on the size of the data. Both iPhones are not available during data transfer.