How to get the DPI Scale of UMG at runtime in Unreal Engine 4 C++

GettingDPI_Scale_UMG_UE4_example.cpp

// this function requires the UserInterfaceSettings header to be included
#include Runtime/Engine/Classes/Engine/UserInterfaceSettings.h

// this function can be marked as Blueprint Pure in its declaration, as it simply returns a float
float MyBPFL::GetUMG_DPI_Scale() {
  // need a variable here to pass to the GetViewportSize function
  FVector2D viewportSize;
  // as this function returns through the parameter, we just need to call it by passing in our FVector2D variable
  GEngine->GameViewport->GetViewportSize(viewportSize);

 // we need to floor the float values of the viewport size so we can pass those into the GetDPIScaleBasedOnSize function
  int32 X = FGenericPlatformMath::FloorToInt(viewportSize.X);
  int32 Y = FGenericPlatformMath::FloorToInt(viewportSize.Y);

  // the GetDPIScaleBasedOnSize function takes an FIntPoint, so we construct one out of the floored floats of the viewport
  // the fuction returns a float, so we can return the value out of our function here
  return GetDefault<UUserInterfaceSettings>(UUserInterfaceSettings::StaticClass())->GetDPIScaleBasedOnSize(FIntPoint(X,Y));
}

Shoutout to Unreal AnswerHub user "Elringus" as they posted an example of using the Engine APIs required to write this function.