The Catholic Church can never change it’s teaching.
Christ is the Mediator and Fullness of All Revelation.
"In many and various ways God spoke of old to our fathers by the prophets, but in these last days he has spoken to us by a Son."26 Christ, the Son of God made man, is the Father’s one, perfect and unsurpassable Word. In him he has said everything; there will be no other word than this one. St. John of the Cross, among others, commented strikingly on Hebrews 1:1-2:
In giving us his Son, his only Word (for he possesses no other), he spoke everything to us at once in this sole Word - and he has no more to say. . . because what he spoke before to the prophets in parts, he has now spoken all at once by giving us the All Who is His Son. Any person questioning God or desiring some vision or revelation would be guilty not only of foolish behavior but also of offending him, by not fixing his eyes entirely upon Christ and by living with the desire for some other novelty.
27
Source:
vatican.va/archive/catechism/p1s1c2a1.htm
Christ revealed God perfectly and completely. The Lord Jesus entrusted the entire and complete Sacred Deposit of Faith to the Apostles, who in turn handed it down to their successors. The Catholic Church still possesses this Sacred Deposit of Faith in its complete entirety. The Church has taught the entire Apostolic faith throughout the ages without adding or subtracting anything from it. The Church can never change its teaching, it can only pass on what it has received from the Lord Jesus through the Apostles.
However throughout the ages, the Holy Spirit has helped the Church better understand the truths which make up the Sacred Deposit of Faith.
94 Thanks to the assistance of the Holy Spirit, the understanding of both the realities and the words of the heritage of faith is able to grow in the life of the Church:
- “through the contemplation and study of believers who ponder these things in their hearts”;57 it is in particular “theological research [which] deepens knowledge of revealed truth”.58
- “from the intimate sense of spiritual realities which [believers] experience”,59 the sacred Scriptures "grow with the one who reads them."60
- “from the preaching of those who have received, along with their right of succession in the episcopate, the sure charism of truth”.61
Source:
vatican.va/archive/catechism/p1s1c2a2.htm
Doctrines never change, but they can develop as our understanding increases over time. Once a doctrine of the faith has developed fully, it may be defined as infallible. An example of this is the Immaculate Conception. The Church, with the assistance of the Holy Spirit was gradually able to arrive at the full truth concerning the conception of the Blessed Virgin. The doctrine was always implicitly understood and believed, but over time the Holy Spirit helped us understand the doctrine in its entirety. It was only then that the Church infallibly declared and defined the doctrine of the Immaculate Conception.
There are many theological opinions about certain doctrines of the faith. Over time, and with the help of the Holy Spirit, the Church will decide whether these opinions make the truths of the doctrine more explicit.
The short answer to your question is that the doctrines of the faith never change, but as our understanding of them increases, the doctrines may develop.