Hello!
Apple’s "Transfer or Reset iPhone" feature, also known as "Get Started" or "Quick Start", is designed to facilitate the complete transfer of data from one iPhone to another including music, photos, apps and settings. This feature was introduced with iOS 12.4 and continues to be supported in later versions of the operating system.
Therefore, if your new iPhone 16 is upgraded to an iOS version that supports "Get Started Now" and your personal music library is currently stored locally on your iPhone 12, you should be able to transfer the entire music library, including custom playlists, using this feature.
However, it is important to note that the "Start Now" feature requires both devices to be physically close together and with Bluetooth enabled during the transfer process. Also, make sure both iPhones are connected to a stable Wi-Fi network and have enough power to complete the transfer.
If, for any reason, the transfer via "Start now" does not work or is not possible, there are alternative methods to transfer your music library:
1. Backup and restore via iTunes or Finder: You can fully back up your iPhone 12 to your computer using iTunes (on Windows or macOS Mojave and earlier) or Finder (on macOS Catalina and later). Afterwards, you can restore this backup on your new iPhone 16. This method transfers all data, including music stored locally.
2. Using third-party tools: There are applications like Coolmuster Mobile Transfer that allow you to selectively transfer data between iOS devices. These tools can provide greater flexibility in transferring specific types of data, such as music.
In summary, Apple has not made any changes that prevent the use of the "Start Now" feature to transfer your personal music library from an iPhone 12 to an iPhone 16. Therefore, you should be able to use the same process that you used previously to transfer your data to the new device.
I hope I helped you!