Is there a plural form for the word etiquette?

No, "etiquette" is already a plural word. It refers to the rules of proper conduct and behavior in a particular situation.

The word is derived from the French word "étiquette," which originally referred to the labels that were attached to bottles of wine in the royal court. These labels indicated the appropriate time and occasion for drinking each type of wine.

Over time, the word "étiquette" came to refer to the rules and protocols of courtly behavior, and eventually became the English word "etiquette."