Ok, but if I have 2 variants inside the same layout,so, how to load the right variant? Or should be only one variant per layout?
The best options is to have only one Layout for Portrait (vertical), and if needed one more Layout for Landscape (horizontal).
Edge case will bring you to have 2 more Layouts to manage Tablet screens, but for now focus on to obtain 1 single layout that adapt everywhere correctly.
Working with Anchors and Designer Script should allow you to obtain a nearly universal layout that will adapt to every screen.
Sadly in the Android world there isn't a standard screen ratio for displays.
So sometimes maybe it will happen the need to manage some particular case.
But even these cases could manage correctly your layout if well designed.
Anyway, in the case that you still want to have 2 different layouts for small screens and large screens you could try something like this:
Root = Root1
Dim ScreenSize As Double = GetDeviceLayoutValues.ApproximateScreenSize 'Detect the approximate screen size of the device in inches
If ScreenSize < 4.5 Then 'Condition for Small Screens
Log("Small Screen")
Root.LoadLayout("small_screen_layout")
Else 'Condition for Large Screens
Log("Large Screen")
Root.LoadLayout("large_screen.layout")
End If
This is just a simple example to make the decision.
But I suggest you to work to make one good adaptable layout.