I've always found multiple monitors terrible for my neck / back, at least if you use them a lot. Ultrawides have the same issue. I'd probably only actually use the middle of them ;)
I binned my multi-monitor setup years ago and went for a 4k 16:9, but even then I generally only use the 4:3 area in the middle 90% of the time. I'd actually prefer a squarer monitor than a wider one, at least for coding.