Quotation marks show that it's a quote. That's why they're called quotation marks.

There's no need to italicize the words quoted unless you want them to stand out (or your boss told you to). I believe if you're citing the ISO standard by name, MLA says you would italicize it. Example:
According to
ISO 9001:2015, "The organization shall identify, review, and control changes..."
Obviously here on the forums you'll see a mixed bag of just about anything.