Apologies, but I’m not sure I understand what the original request or challenge is?
You could create a rule that sets multiple bulbs/devices to a specific dim level… then either manually run that rule or have it triggered at a certain time.
I think @James is saying that if the power source to the light bulbs is shutoff, then they won’t receive commands. So if the smart bulbs are in a lamp, but the physical switch to the lamp is off, then the bulbs won’t receive commands.
Compare that to having the lamp switch always on and making sure the smart bulbs are always turned off via commands (eg. mobile app or rule or whatever), then the bulbs can still receive commands when they’re still off.
The other challenge is that with most bulbs, when you set the dim level it will also turn the bulb on which may or may not be what you want.