There are a couple of different custom smart apps that will do what you want. One is dim and dimmer, and another one is dim with me. Also one of the scene setting apps like scene machine will probably do it. I can’t remember if the big switch does dimming as well or not. And Tony just posted a new app this week called FlexiLight that has a whole bunch of parameters.
Anyway take a look in the community created smart apps category and see what you find there.
edited to add
I just checked, and the big switch does do dimming, although it doesn’t do color setting. But it might be all you need. Basically you pick any one switch or bulb on your network and then tell selected other switches/bulbs to copy what it does.
It’s one of the officially supported smart set up smartapps, so it’s really easy to install, no custom code is needed. You’ll find it in the convenience section.