The best way to get cool party light effects is to buy a hue bridge and lights that work with those (the hue brand has the best color renderings, but there are less expensive brands that work with the system as well, including IKEA and INNR) and then get any of several third party hue special effects apps.
There are lots of apps to choose from. Here’s a good recent article covering several.
What does all of this have to do with SmartThings? Nothing. SmartThings is dismal at party lights, no matter which route you take to creating automations. It doesn’t have a good “groups“ feature and it doesn’t have dynamic scenes, both of which are pretty much essential for real party lights. It also doesn’t do groupcasting, which is a technical term that has to do with getting a group of lights synchronized rather than creating an unintended “popcorn effect“ where one light in a group changes color before the others. It can’t sync light changes to music.
So for your purposes, I would return the smartthings hub and shift to the Hue ecosystem. It doesn’t handle as many kinds of devices as smartthings does, but you can always come back to SmartThings later (it has an integration with Hue) if you decide you want to buy a smart washing machine or something else hue doesn’t support.
For now, for great lighting effects and a really good app to manage them, smartthings is not what you want. And nobody does it better than Hue although it does cost more than some of the other options.
Yeelight is a cheaper alternative which tries to promise everything hue does, but it doesn’t have as many features, it’s harder to set up effects, and, worst of all, it disconnects a lot. It’s worth considering, but this is one of those cases where you do get what you pay for and hue is just a better system.
Here’s a review of yeelight if you’re interested.