The Catholic Church did not “change” the bible, but the Catholic Church did define what was in their bible.
If you think about it, if you are operating a “world wide” organization you need to have everyone on the same page. You need to get together and come up with a standard set of operating rules.
When you take the “religion” out of the “bible process”, it makes perfect sense that some stuff had to be left on the editing floor.
But like the many men claiming to be of the God of Abraham, that which was of God became established as being such not because of magisterial decree, but progressively over time, without compulsion, essentially due to their heavenly qualities and attestation, like as with true men of God, even despite magisterial opposition. Thus did the NT church begin and continued.