2016 Camry se weird knocking noise

The car has 350k miles,I’ve knocking coming from engine area only in cold start only noticeable when with the a/c on or I shift to R or D but barely I can hear it on neutral and 90% disappears after couple minutes of driving , the driving and fuel consumption is good no major problems whatsoever,went to Toyota dealer to diagnose they recommended to change the intake cam phaser and time chain assembly cost 6000$ , surprisingly the knocking still unchanged and the Forman mechanic suggested to change the engine next fix😤, any suggestions other than buying new car .