Input_Datetime - How to update value

Can input_datetime have its value set by automation?

I’ve tried the following automation:

- alias: input time value
  trigger:
    platform: state
    entity_id: sensor.xyz
  action:
    service: input_datetime.set_datetime
    data_template:
      entity_id: input_datetime.only_time
#      value: '{"entity_id": "input_datetime.only_time", "time": "09:03:01"}'
#      value: '09:03:01'
        value: '9:03'

where a change in state of sensor xyz should change input_datetime.only_time to 09.03

this seems to work.

- action:
  - data:
      entity_id: input_datetime.only_time
      time: 09:03:01
    service: input_datetime.set_datetime
  alias: tester1
  trigger:
  - entity_id: switch.test
    platform: state