Are all rulers (presidents, kings, prime ministers, etc) under the authority of Christ?
John 19:11 “You would have no authority over me at all,” Jesus answered him, “if it hadn’t been given you from above. This is why the one who handed me over to you has the greater sin.”
Mat 4:8 Again, the devil took him to a very high mountain and showed him all the kingdoms of the world and their splendor. 9 “All this I will give you,” he said, “if you will bow down and worship me.”
Eph 2:2 in which you previously walked according to the ways of this world, according to the ruler of the power of the air, the spirit now working in the disobedient.
1Pe 5:8 Be clearheaded. Keep alert. Your accuser, the devil, is on the prowl like a roaring lion, seeking someone to devour.
But:
Mat 28:18 And Jesus came up and spoke to them, saying, “All authority has been given to Me in heaven and on earth.
Luk 10:18 Jesus told them: I saw Satan fall from heaven like a flash of lightning.
Col 2:15 He disarmed the rulers and authorities and disgraced them publicly; he triumphed over them in him.
Jde 1:6 And the angels—who did not keep their own position of authority but deserted their proper place—He has kept in everlasting shackles under gloomy darkness until the judgment of the great Day.
Rev 20:2 He seized the dragon—the ancient serpent, who is the devil and satan—and bound him for a thousand years.
Conclusion: Jesus has the ultimate authority. But satan, although chained, is still ruler of the power of the air. People, including rulers, still have the free will to choose to follow him, but they don't have to:
Jam 4:7 Submit yourselves, then, to God. Resist the devil, and he will flee from you.