Opinions of historians differ on that.
(Rev 5:1)
"And I saw in the right hand of him that sat on the throne a book written within and on the backside, sealed with seven seals."
The description of what John saw. He clearly described a book with seven seals. Since he saw them, it wouldn't be unreasonable to suggest they were on the outside of the scroll, not on the inside of the document. The seals are not hidden from view. If the seals are on the outside, all seven must be opened before the contents of the book are revealed.
Robert van Kampen owns one of the world's most extensive private collections of biblical manuscripts, with many dating back to the second century. He writes in his book, "The Sign," that of the many scrolls in his possession not one has a seal on the inside. When sealed, the scrolls are all done so from the outside. When one seal is present, it was usually placed there by the author of the scroll. When more than one seal is present it indicates a series or set of conditions that must be met before the scroll can actually be opened. He also cites that the Shrine of the Book located on the grounds of the Israel Museum in Jerusalem has many scrolls that have multiple seals placed on them, yet not one scroll has a seal on the inside.
What is the scroll that John saw?
Ezekiel might have a clue.
Ez 2:9-10 "And when I looked, behold, an hand was sent unto me; and, lo, a roll of a book was therein; And he spread it before me; and it was written within and without: and there was written therein lamentations, and mourning, and woe."