How did Emperor Augustus change the Roman Republic?
Augustus was made consul after his defeat of Cleopatra and made a big show of relinquishing his dictatorial powers to the Senate. However, he wasn't done exercising his newfound power to reshape the Republic in ways he thought appropriote.
Augustus was able to retain the loyalty of the army and keep contorl of most of the Republic's finances, which allowed him to do as he saw fit despite what objections the Senate may have had. They even went so far as to make his obvious power constitutional by making him commander of the provinces for ten-years.
Augustus revived the ancient religious rites and ceremonies from the earlies days of the Republic. He created a police force and developed the Praetorian Guard. He passed several marriage laws which outlawed adultry and rewarded children.
Augustus insured leave for soldiers with families and instituted a system of discipline where riotus behavoir was met with decimation (executing every tenth man)