Answer:
The hyperbole is used to accentuate the King's power.
Step-by-step explanation:
In this excerpt the hyperbole is seen throughout he whole quartet. The first line that could lead to think so is "The crown upon your brows may flourish long," where the crown is highlighted as a sign of power, and flourish would mean to maintain or preserve this power. Then, the use of "Sceptre" exhibits the will to conquer other lands, which again, refers to the king's power.
At the end "And all with love and readiness obey!" refers again, to the power, but this time over the people. It's important to remember that Kings were the supreme authority, and therefore people owed respect and admiration to them. That, again, takes the reader to understand how powerful this king was, not only in his kingdom and with his people, but also between other nations.