Answer: It depends on who is the king is and how they are giving the speech
Step-by-step explanation:
If they are a well respected ruler who knows how to rule and manage a country and not do cruel things to the people, then they probably would most likely be a more powerful public speaker then normal. So depending on how memorable that king has done good for the people or if they benefited lets say human rights or established a strong relationship with nearby neighbors like Canada and America. Then I would say that there public speeches could be more powerful then on average