In the book 1984, Winston and Julia lived under the rule of a tyrannical government.
Yes, you can use tyrannical in a sentence..
Example sentence - The king would be considered tyrannical by most subjects.
Josef Stalin was the ruthless, tyrannical leader of the Soviet Union. He was tyrannical, demanding that even his smallest wishes be obeyed instantly.
I have a tyrannical teacher who asks me to use really difficult words in sentences out of shear spite.