Over the air TV and sub-channels

[Just Retired]

Several. I prefer TV Fool, but there are others. The good ones will also tell you why KOCO (and probably KETA) can be a little more difficult. Spoiler alert: VHF.

http://www.tvfool.com/

https://antennaweb.org/

https://www.tablotv.com/tools/

Look for the app: Antenna Point. It shows where the towers are and how to adjust your antenna.
The app NoCable lists the available channels and provides a TV Guide. Both are on the Google Play Store.