Superlative adjectives are indeed used to describe a relationship between three or more things. They are employed to indicate that something has the highest or lowest degree of a particular quality when compared to a group. For example, in the sentences "John is the tallest student in the class" and "This is the most interesting book I have ever read," the adjectives "tallest" and "most interesting" are superlative adjectives indicating that John has the highest degree of height among all students and the book has the highest degree of interest among all books the person has read.
Thus, the correct answer to the question is:
True
