Is less a preposition

Answer 1

It can be, when the word less means "minus" or "except."

Example: The total, less the tax, is one hundred dollars.

Otherwise less, without an object, is an adjective, adverb, or noun.

Answer 2

"Less" is an adverb or determiner used before an adjective or adverb to indicate a smaller amount or degree. It is not a preposition as it does not show the relationship between a noun and another word in a sentence.