In autocratic regimes, what is the main purpose of the legislature?

To guarantee the power structure

Explanation:

Unlike in democratic government settings where the legislature is meant to have people's representatives in the government formation and decisions, in an autocratic government, the main purpose of the legislature is to guarantee the power structure. This is to make sure that there is a form of legitimacy to the government.

Hence, in autocratic regimes, the main purpose of the legislature is to guarantees the power structure.