I have heard Jewish believers in Christ say the New Testament does notreplace anything in the Old Testament. But it seems to me that unless the New Testament does not apply to Jewish believers, then at least some things HAVE been changed with the New Testament.
Paul chastised Peter for buckling under to the circumcision group in Galatia (Gal 2:11-16). That’s part of the whole point of that book - the freedom we have in Christ.
Paul was clear that the purpose of the law was to lead us to Christ.
Now that faith has come, we are no longer under the supervision of the law (Gal 3:19-25).
In fact we see in Gal 3:26-29 that we who have faith in Christ are not Jew nor Gentile, but the children of God.
Gal 5:1 It is for freedom that Christ has set us free. Stand firm, then and do not let yourselves be burdened again by a yoke of slavery.
Gal 5:11 Brothers, if I am still preaching circumcision,
why am I still being persecuted in that case the offense of the cross has been abolished.
Circumcision is now of the heart instead of physical. Titus was not circumcized (Gal 2:3).
Col 2:11 In him you were also circumcised, in the putting off of the sinful nature,
not with a circumcision done by the hands of men but with the circumcision done by Christ
We are free to eat and drink as we wish, and free to celebrate which ever festival days or sabbaths we wish.
Col 2:16 Therefore do not let anyone judge you by what you eat or drink,
or with regard to a religious festival, a New Moon celebration or a Sabbath day.