No. They are all the same singular.
The word ravioli is taken from Italian. It is the Italian plural of raviolo. In most contexts, you would use "ravioli" as the plural. There were a hundred ravioli in the box. The dictionary does list "raviolis" as an alternate plural form, but you should generally avoid using it.
There is no plural form. Do and Do not are verbs
Ravioli vegetariani is an Italian equivalent of the English phrase "vegetarian ravioli." The masculine plural phrase models a linguistic difference whereby Italian tends to have adjectives follow, not precede, their nouns. The pronunciation will be "ra-VYO-lee VEY-djey-ta-RYA-nee" in Pisan Italian.
The plural form of him, her, or it is them. (objective pronouns)
Bridges is the plural form of bridge.
The plural form of "was" is "were."
The plural form of "I" is "we."
The plural form of "is" is "are."
"Groceries" is the plural form of "grocery."
"Beliefs" does not have a plural form, as it is already plural. Beliefs is the plural form of belief.
The plural form of mouth is mouths. The plural form of month is months. The Mounth is a range of hills in Scotland and does not have a plural form.