I'm on the other side of this one. Two 27" 4k displays (at 2x scaling, so logical 1080p), always with editor on one screen, and documentation on the other.

This is true for programming (where editor = IDE and documentation = API docs for some thing or other), 3d modelling (where editor = CAD software, and documentation = reference drawings, diagrams, etc), and even gaming (where "editor" = Blue Prince, and "documentation" = a gigantic Obsidian vault with all my notes).

In all of those cases, I'm decidedly not multitasking. I have multiple applications running, but they're all contributing to the task at hand. Instead, I find that things having a fixed position in space they live in, and not needing to cmd-tab and find the right window/application are two things that help maintain focus.