If you want to combine Coffee On Time into the secondary info line, you can use a mushroom-template-card (mushroom card).
Off:
On:
In the GUI configuration, paste the following into the secondary information section:
{% if is_state("switch.coffee_machine", "on") %}
{{ relative_time(states.switch.coffee_machine.last_changed)}}
{% else %}
{% endif %}
This will display the time since switched on, or nothing if the switch is off.
If you want the usual icon_color response, use this complete yaml definition:
type: custom:mushroom-template-card
primary: Coffee Machine
secondary: >-
{% if is_state("switch.coffee_machine", "on") %}
{{relative_time(states.switch.coffee_machine.last_changed)}}
{% else %}
{% endif %}
icon: mdi:coffee
entity: switch.coffee_machine
icon_color: >-
{% set entity_state=states(entity) %}
{% if entity_state=='on'%}
accent
{% else %}
grey
{% endif %}
tap_action:
action: toggle