The first rule of home automation applies: “the model number matters.”
If your smart bulbs are hue bulbs attached to a hue bridge, it’s easy: Hue offers a “power on” feature which let you set the desired behavior for each individual Bulb, either turn on or come back with whatever the setting was before the power outage. Very nice, and works well.
If you are using a different brand which connects directly to the smartthings hub, some of these, but not all, can report to the hub when power is restored. So one community member has created a “canary“ smartapp which can recognize when a Bulb which is normally always off gets turned on, and then use that to trigger whatever you want to have happen with your other bulbs, typically to have them turn off. (The topic title is a clickable link.)
