Can you help me to better understand what you are referring to here as “design layout”? Are you talking about design options?
If that’s the case the Revit plugin loads the active design option from the model. If you want to switch between the design options you can do that using the Revit UI, and then use the Pollination plugin to export that option.
Thanks @mostapha, I think I found the answer, it is right that it takes the active layout, but it seems we have to disable/enable pollination to reset the new layout when you change it, otherwise it still has the old layout in the memory, which might be sth that worth updating in next versions.
@ksobon clarified this behavior for me but I forgot to document it for you. Based on his input, for Pollination to parse the design option you have to make it the primary option. Selecting the option is not going to make it the primary option.