To be clear, there is a fundamental difference between "scripture" and "canon". A biblical canon refers to a fixed collection of scriptures. One good indicator of the status of a writing as scripture is the care with which the community recorded it. Codices and actual books were very rare and treasured during 2nd and 3rd century A.D. If the community regarded something as scripture, they put it in a codex nearly entirely. This is not true for secondary sources. About 65% of 2nd-3rd century copies of other Christian literary text such as theological treatises, other gospels etc. made it into codices, the rest were left in rolls or only recorded as rolls.
So, copying a text in a codex doesn't necessarily mean it was regarded/treated as "scripture". But I contend that copying a text on a roll, for most 2nd-3rd century Christians at least, meant that the text (or at least that copy of it) wasn't regarded as "scripture".
Flashback about 600 years to the Ancient Near Eastern Jews. Each community had slightly different requirements. The Pharisees, Sadducees, Zealots, and Essenes were all subsets of Jews and all viewed scripture differently. And noone has codices. How are we going to figure out what they thought was canon?
They best way to is to look for commentaries on "books" to see if the community valued it:
(1) the existence of pesherim, midrashim, or other forms of commentary on a text is strong evidence that a community regarded the scripture as sacred. This is because writing is painstaking, so the book must be revered if the community would spend valuable time simply commenting on the text and not copying the text itself. Pesherim exist for the following writings: Deut, 2 Sam, Exod, Amos, Pss, Ezek, Dan, and Isa (4Q174); Deut, Num, and Josh (4Q175); Isa and Zech (4Q176); and Pss, Isa, Mic, Zech, Ezek, and Hos (4Q177). People describe Pesherim for Isa, Hos, Mic, Nah, Hab, Zeph, and Pss.
It is noteworthy that among the extant examples of the chief genres of exegetical literature of the first six centuries -- there are none for Ben Sira, Wisdom of Solomon, Judith, Tobit, 1-2 Maccabees, 1 Esdras, 2 Esdras, Ezra-Nehemiah, or Esther.
Another good way is to see if there is parabiblical literature describing the event in question. This includes a midrash. These are imaginative expansions of events that occured in scripture. They are not scripture, but "books" they expand upon are scripture. The following figures and retelling of events and thus the "books" they are a part of should be considered scripture: Enosh, Lamech, Noah, Shem, Ham, Japheth, Abraham, Book of Giants, Enastr, Book of Dreams' Letter of Enoch, Birth of Noah, Jacob, Testament of Judah, Joseph, Naphtali, Levi, Kohath, Amram, Moses, Jubilees/Aporcryphon of Moses, Apocryphon of Joshua, Samuel, and Ezekiel. Jubilees in particular enjoyed authoritative status and had its own pesherim. The Damascus Document [Cairo Geniza A] 16:1-3 promotes the authority of Jubilees.