Welcome! The official rules engine in the new app is somewhat easier to use and has more options than one in the classic app, so that’s something else to consider. You can use both apps at the same time if there are features that you want in both.
Otherwise, as @jkp Mentioned, start with the official “smart lights” feature in either of the two apps and see if you can do what you want there first. That’s the option that will run local, it’s newer than routines in the classic app, and it’s really the one that smartthings intends you to go to first even for many devices other than lights.
You might also find the following FAQ of interest (the topic title is a clickable link)
The official rules engine in the new app is somewhat easier to use and has more options than one in the classic app, so that’s something else to consider. You can use both apps at the same time if there are features that you want in both.
