How did plebians gain a larger role in Roman Republic?
Augustus’ settlement of the constitution after his victory in the civil wars over, first the killers of his adoptive father Julius Caesar, then Mark Antony, rested principally on his assumption of lifetime powers of a Tribune of the Plebs. He didn’t take on the office, just the powers, which meant he didn’t have to be elected annually. This gave him immunity from prosecution, a veto over laws and the ability to introduce laws. Very clever. And by this move, and gaining personal control of the legions by allocating to himself the provinces which had legions, he was able to eliminate the power of the Centuriate and Plebeian Assemblies. His ‘restoration of the Republic’ in 27 BCE was in reality elimination of the mechanisms of the Republic, and set the progressive roadmap of imperial control, which culminated by the 3rd Century CE in despotism.