"Modifying" is a technical word in grammar. You may read about the technical meaning: Grammatical modifier. In this sense, attributive adjectives are modifiers, and may modify a noun to make it more specific.
However, I understand your question to be: are attributive adjectives restrictive or non-restrictive? This is the distinction between:
There are three men. The man that is friendly is named James.
This modifying relative clause is restrictive. It specifies which man of the three.
There is one man. The man, who is friendly, is named James.
This modifying relative clause is non-restrictive. It gives additional information about the man but does not specify.
Attributive adjectives are ambiguous and can indicate both restrictive and non-restrictive senses. I could replace both sentences in the examples above with "The friendly man is named James." The context would imply the meaning of that sentence to be restrictive in the first case and non-restrictive in the second.
This ambiguity can give unintentional humour. Consider the sign in a supermarket:
If you can't find what you are looking for, our friendly staff will be glad to help.
The intention is non-restrictive and means that "all our staff are friendly and helpful". But if you read it as restrictive you get an ironic, "... our friendly staff will be glad to help, but the unfriendly ones will be unhelpful"!
In this case, there is ambiguity, but it is resolved pragmatically by context. In other cases there is ambiguity but it doesn't matter.
Look at that red cat!
Could mean "Look at the cat that is red!" or "Look at the cat, which is red!" It really doesn't matter which.