Automation that turns a light on to 50%?

How do you set an automation that when triggered, turns on a light 50% brightness?
Thanks

Put this in the action block, replace the light entity with yours:

action: light.turn_on
target:
  entity_id: light.mylight
data:
  brightness_pct: 50

Do you mean “add building block”?

Put this in the action block → Light: Turn on

Ok I will give this a try. Thanks guys