Question

"what happened to king louis xvi during the french revolution?"

Answer 1

The French didn't want to be ruled by monarchs anymore, but wanted to become a republic without "tyrannizing" monarchs that they thought spend all their tax money and wanted equality, and also no more nobility with all their benefits and privileges.
The revolutionists captured King Louis XVI and Marie Antoinette, held them prisoners and eventually had them beheaded by a guillotine in 1793.

Answer 2

King Louis XVI was first made a constitutional monarch, then removed from power, then executed by guillotine.

The French Revolution became increasingly more radical as it progressed. The king, Louis XVI, first was forced into accepting a government in which the Legislative Assembly held the main power and the king was no longer personally in charge of government. When France declared itself to be a republic in 1792, the king was removed from power entirely. On January 21, 1793, Louis XVI was executed, under charges of conspiring with foreign powers against the Republic of France.