Those would be your first two clues as to it's age.
“Those would be your first two clues as to it’s age.”
That would only tell us how old the oldest surviving copy is and who was the first to mention the Book of Revelation in writing. There are, for instance, fragmentary passages of Revelation in the writings of the Early Church Fathers dating from the second century. That only tells us it was written before then and was known by then. It doesn’t tell us when it was written. The oldest actual copies - in toto or in fragments are more recent. So that would only tell us that we have fragments and whole copies from the third or fourth century. That doesn’t tell us when the book was written.
The internal evidence can only give us some ideas as to when it was written. Nothing is guaranteed other than that range of years. The fact that the Temple’s destruction, and Jerusalem’s destruction, is not described as an accomplished fact might suggest it was written BEFORE A.D. 70. The fact that 666 = Nero would strengthen that suggestion since he died in 68. Other factors suggest it was written as the late 90s, however.
Having had to assign dates to medieval mss. when I was in graduate school I can tell you this is sometimes a very technical business. Perhaps the most accessible book for an early dating of Revelation is Gentry’s: https://www.amazon.com/Before-Jerusalem-Fell-Dating-Revelation/dp/0982620608
Age of a manuscript doesn’t necessarily confirm anything. The apostle Paul said there were people passing around spurious letters as if he had written them. I suppose if one of them cropped up, there would be consternation.