How get value from IFTTT to Home Assistant?

Hi everyone.
I tried to download data from ifttt to Home Assistant or Node-Red for a few days.

in the webhook, insert the body section

{“entity_id”: “temperature.ust_boiler”, “value”:" {{NumberField}}" }

The parameter “value” is needed for setting the temperature in my boiler. (A thermostat is installed in the boiler, which gets this value through MQTT.)

For now, I was able to read this parameter in Node-Red, but I have no idea what to do next.
How to isolate it and send it through the MQTT to the boiler?
I would like to read it in Home Assistant, have a sensor to see the settings.

Does anyone have any idea how to do it?