Data template for start date on service google.add_event

I can not for the life of me figure out the data template for the start date requirement on the service google.add_event
It requires a start date and an end date but I want those to be dynamic and start and end on the same date the automation was triggered so I figured I would use {{ states(‘sensor.date’) }} to report the date in the format that it is expection but i get a “no parseable data” error

service: google.add_event
data:
  calendar_id: "My Calendar"
  summary: 'Boiler runtime for the month is "{{states.sensor.boiler_time.state}}"
  start_date: "{{ states('sensor.date') }}"
  end_date: "{{ states('sensor.date') }}"

It does work if I manually type in exactly what that sensor state would return anyways…

I’m having the exact same problem. Anyone have a solution?
Thanks !

EDIT: I managed to make mine work writing this:

start_date: "{{states('input_datetime.day_1')}}"