You need to check if GetPhysicalScreenSize()'s second return is >= 1200; if it is, modify SDPhantom's method to scale UIParent.
Code:
local physicalWidth, physicalHeight = GetPhysicalScreenSize()
local pixelPerfectScale = 768 / physicalHeight
if physicalHeight >= 1200 then
UIParent:SetScale(pixelPerfectScale)
else
SetCVar("useUiScale", 1)
SetCVar("uiScale", pixelPerfectScale)
end
Source:
https://wow.gamepedia.com/UI_Scale#P...ct_UIs_and_you