Output Celcius from Kelvin mqtt sensor

Configuration
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1

I have a mqtt sensor reading temperature, but it is in Kelvin. How can I convert it to Celcius (-273) for the sensor?

  - platform: mqtt
    state_topic: "environment.inside.mainCabin.temperature"
    value_template: "{{ value_json.value }}"
    unit_of_measurement: "°C"
    name: "CabinTemperature"
2 
value_template: "{{ value_json.value | float - 273 }}"
3

Thank you so much!