This is a great question. It is very clear that the Romans used art as propaganda. Let me give you a number of examples.
First, one of the greatest ways Roman leaders used artwork to make themselves look great was through the use of coins. Roman coins were struck with various images to make political and ideological points.
Second, Romans also dedicated shrines and temples to show off as well. For example, when Cicero was exiled from Rome, he set up a shrine to Minerva, who was known as a protector of the city. By associating with Minerva, he was telling the people that he was also a protector of the city in view of his role in bringing down Catiline and his conspiracy. In other words, in his exile, Cicero wanted the people to know all that he did to protect the city, so that they would call him back.
Third, the Romans also used written art, that is, poetry toward this end as well. Think of Augustus and Vergil and Horace.
One of the great examples of art used for propaganda is Julius Caesar’s Commentaries on the war in Gaul.
Although most Roman intellectuals wrote in Greek, Caesar chose Latin because he was writing to the people of Rome. He took care to mention, often by name, many of his centurions, detailing their exploits, along with those of his army, and thus endearing them in the hearts of the people. These "dispatches from the front" were not only popular with the people, but would eventually be recognized as the finest Latin prose ever written.
Caesar well understood the value of symbolic acts on a grand scale. His two invasions of Britain brought little in the way of treasure or territory, but the propaganda effect on the people of Rome was huge. As Tom Holland noted in his book, Rubicon, to the Roman people the invasions of far distant Britain was like our own landings on the moon.
It should also be noted that when it came to portraits, either on coins or in sculpture, until the Principate women were conspicuous by the absence. Thus the scandal when Antony had coins struck, to pay his legionaries, which featured his face on one side and the face of Cleopatra on the other. This lack of female portraiture would soon change with the reign of the Julio-Claudian emperors. First Livia, wife of Augustus, and then other women of the imperial family were rendered on coins and sculptures that eventually appeared throughout the empire. This was a tacit acknowledgement of the role these women played in the running of the Empire, even though “officially” they had no role at all.
Rubicon The Last Years Of The Roman Republic by Tom Holland
Caesar's Wives - Sex, Power and Politics In The Roman Empire by Annelise Freisenburch
Antony and Cleopatra by Adrian Goldsworthy
The Gallic Wars by Gaius Julius Caesar