You need to transfer music from your iPhone 7 to the PC using CopyTrans: https://www.copytrans.net/support/manual-backup-to-pc-how-to-transfer-music-from-an-iphone-ipad-or-ipod-to-a-folder/

After you have all your music saved on the PC, you can transfer it to your iPhone 14 Pro: https://www.copytrans.net/support/how-do-i-add-music-and-videos-to-my-ipod-or-iphone/