What do you mean, "the OS as a whole"? This is the OS!
niri msg action focus-window --id $(niri msg --json windows | jq '.[] | select(.app_id=="foot") | .id') xrandr --setmonitor DisplayPort-0-0 1280/297x1440/340+0+0 none
xrandr --setmonitor DisplayPort-0-1 2560/595x1440/340+1280+0 none
xrandr --setmonitor DisplayPort-0-2 1280/297x1440/340+3840+0 none