Setting a climate attribute

If a climate device has an attribute I can retrieve into a sensor like this…

    setpoint_until:
      value_template: >        
        {{ state_attr('climate.honeywell','status')['setpoint_status']['until'] }}

How can I write to that attribute ?

You can’t write to an entity’s attribute directly. You need to use a service to affect the entity. If it doesn’t have a service that can affect it the way you want, then there’s not much you can do.