As long as you have an Over The Air Antenna you can get and watch local Channels on your Apple TV device.
However you can just connect your over the air antenna to your TV Coax connection and get free local channels that way as well.
You cannot get the local channels on your Apple TV device through the internet though.
You'll need local TV coverage that reaches your area to get the local channels on your TV.
Some areas it's impossible to get local TV channels over the air and some places you can easily get local TV channels over the air by just adding a TV antenna to either your rooftop or in your house.
Some areas require an outside over the air antenna and some places you can get the local channels on indoor TV antennas.