Oh.. I think you also need double quotes around template brackets when used as the value in a service call..? Which conflicts with the quotes around the entity and attribute so just use single quotes there.
brightness_pct: "{{state_attr('light.kitchen_sink_ceiling', 'brightness')}}"
Just whipped up a partial example with my living room lights.
It is missing a trigger and an else butI focused on theactionyou had trouble with.
Using brightness instead of brightness_pct seemed simpler. (Or at least if both can usethe same attribute...)
alias: Example
description: ""
trigger: []
condition:
- condition: state
entity_id: light.living_room_floor_lamp_1
state: "on"
action:
- action: light.turn_on
metadata: {}
data_template:
brightness: "{{state_attr('light.living_room_floor_lamp_1', 'brightness')}}"
target:
entity_id: light.living_room_floor_lamp_2
mode: single