I've experimented with many different approaches to display setup over the years. For proper design work, you usually need more than just a laptop screen, and that's where things start to get distracting, especially when you stack multiple displays together.
The extra displays, in my experience, encourage multi-tasking combined with a lack of focus. I experimented with having a separate monitor for Slack & or video chats, but it still felt like too much. So I ultimately settled on having just one display.
I call it the One Monitor Approach™. The rule is that the display can be be as big as you want, a long as there's only one.
My workspace
For a few years now I've been mainly using a 38” LG widescreen as my primary display. The widescreen is perfect for design work without being overly distracting. Sometimes, I'm tempted by the Apple Studio Display, but the price trade-off, as well as the smaller size doesn't seem quite worth it.
The one monitor
Really, the only downside of having a wide screen is not always being able to share the entire screen, especially if a colleague is on a smaller laptop. Besides that, it's great.