I cannot find the write command to use to Power On the TV

I have a Samsung TV UN75CU7000BXZA

I have enabled remote and wifi capability to power the TV on. Using the app on my phone without wifi enabled I’m able to turn off and on the tv. How can I turn the TV On using the API?

@VartanA Welcome to SmartThings Community

In that case, you can use the my.smartthings.com to see your device’s capabilities. once you identify what capability you are interested in, you can send a command.

This is the endpoint to send a command:
https://api.smartthings.com/v1/devices/{deviceId}/commands
This is an example of the payload:

{
  "commands": [
    {
      "component": "main",
      "capability": "colorTemperature",
      "command": "setColorTemperature",
      "arguments": [
        "30000"
      ]
    }
  ]
}

Official Documentation here

If you are interested in seeing the capability definition (for example: see the commands)

Note: Also you can use the API or the SmartThings CLI