The only form of identity Roman citizens carried was a note from the censor administering a wheat subsidy. In AD 79, citizens paid only two sesterces for every eight cubic liters of wheat. The normal price fluctuated between seven sesterces and 1.74 denarii.
Furthermore, Roman citizens were required to wear a toga in the Roman forum and at official events. A plain white tunic for proletarians cost less than 100,000 denarii.
Those with a red band for the “equites” order cost between 100,000 and 249,000 denarii.
And those with the widest purple sash for the order of senators were worth over 250,000 denarii.
In general, it was a different mentality. It was the authorities who had to prove the identity of others, not the other way around. Therefore, St. Paul claimed to be a Roman citizen. So the Roman magistrates shit themselves because they illegally beat a Roman citizen. Since Paul was a tentmaker, his family obtained Roman citizenship by supplying their tents to the Roman legions.
Slaves used a kind of bronze plate with their name and the name of the neighborhood where they lived.
Those released wore a red cap.
And pilgrims or citizens not subject to Rome wore their traditional clothes.