Try turning on your Apple TV (using the Menu/Back button or the TV/Home button), to have that send a CEC signal to the TV to wake from standby as well.
CEC should be activated in settings on both the Apple TV box and the TV.
For the Apple TV box: Settings﹥Remotes and Devices﹥Control TVs and Receivers (or*: Turn On Your TV with Your Remote)﹥On
For the TV: See its manual for CEC settings and functionality.
That is all that Apple TV (or any peripheral) can do. The rest is up to the connected devices.
I would expect for many 2014 TVs to have this functionality, but you should ask the manufacturer or other owners of the same model to be sure, as all CEC functions are optional for the manufacturer, except passthrough of the CEC signals. Note that power on and power off are two distinct different CEC functions; one can be supported while the other is not. Try finding Panasonic specific forums or Panasonic specific sections of AV forums.
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*Depending on whether there is a receiver in the setup, the Apple TV Setting may name it differently.