There are lots of smartapps to tell a smart bulb to dim based on the setting of a switch, the bulbs in fact often self identify as dimmer switches to begin with, because they have dimming capability. Or you can use one bulb as the master and have other bulbs follow it.
I’m not sure there’s an officially published app for that at this point, but any of the others should still work.
Have you tried “dim with me”?
@twack is there equivalent functionality to “dim with me” in the new smart lights solution app? Or do people still need to add A custom smartapp to have one dimmer follow another?