Adjectives in English do not become plural if they are followed by plural nouns. The only exception is demonstrative adjectives. Occasionally, a plural noun will be made into an adjective but this is not because of agreement with the noun but because of what the noun refers to, e.g. The Twin Tours disaster led to the deaths of many people.
this book, these books.
that dog, those dogs.
this + singular noun, e.g. this book, this thing, this person
these + plural noun, e.g. these books, these things, these persons
that + singular noun, e.g. that book, that thing, that person
those + plural noun, e.g. those books, those things, those persons
i.e. demonstrative adjectives are the only adjectives in English that agree with the noun in number.
“Both” and “all” are the only adjectives that go in front of the article, possessive adjective or demonstrative adjective.
All the boys, all my books, all those students, both the students, both his friends, both those books.
The captain spoke to all the team.
Both the buildings will be demolished to make way for the new road.