Dim Lights in automation

I’m trying to dim 6 lights in an automation. I have an IKEA 4 button remote and 6 lights are on brightness 80%. What I want is to press a button on the remote so that the lights all dim to 20% brightness. I just can’t find an action (call service) that dims the lights. Only Turn light on/off or toggle. Can someone help me?

The lights are alle Zigbee bulbs in ZHA with Sonoff dongle.

Can you post the automation code you are running? Also, have you tried this:

service: light.turn_on
  entity_id: light.your_light_group
  brightness_pct: 20

docs here:

Thanks! it works.