This is just a guess but if iruma is 5"6 tall which is average for a japanese teen ( i didnt do any deep research just looked through the first site i come across) and if sobnock is 2-4ft taller than him then sabnock might be 7-9ft tall then poro-chan is 2-4ft taller than sabnock then he could be 9-13ft tall then delkira is 2-4ft taller than poro-chan so delkira might be 11-17ft tall, also seeing how small poro-chan compared to the throne delkira might be actually bigger, anyways i dont know if the author officialy disclosed information about their heights as of making this guess