I think you'll have to be more clear about what you mean by "completed." The Bible is not a single book, it's a library of books written at different times by different people and some of them went through stages of editing and updating with material being added. We have no autograph copies of anything so we don't necessarily know what the original "completed" texts would have looked like or what would even count as "completed" in some cases.

Many books of the Bible definitely were changed over time before they were frozen by canonization, but it might not be precisely correct to say that they were altered from complete, pristine originals so much as that they are the final results of larger processes of composition and editing over time.

This is my first high level post here. I hope it is up to snuff. Degree in Religious History.

The Bible is not one, book, but a collection of books. If you mean from the time of canonization, then no. Scribes were famously particular in their process of copying the scripture.

While some books show evidence of having a second author adding material (The "he who is without sin should cast the first stone" story for example.) that was very early on. We know this because in finding old manuscripts that this story was not in there. In other books such as Isaiah, it is suspected because of stylistic differences within the text.

When archeologists uncovered the Dead Sea scrolls, there were portions of Jewish scripture from about 2000 years ago. The text is virtually the same as what we have today. While the texts from the Dead Sea scrolls were still far removed from its original even 2000 years ago, we at least know that since that time they have remained the same

To;dr while some texts show evidence of additions or editing early on, changes have not generally been made once a text is considered canon.

Sources: "How the Irish saved civilization" by Thomas Cahill