All of Scripture is true, so the Gospel shiny be interpreted as contradicting OT laws and vice versa. In Matthew 4:15-23, Jesus began his ministry with the Gospel message to repent for the Kingdom of God is at hand, which was a light to the Gentiles, and OT laws were how his audience knew what sin is, so repenting from our disobedience to them is a central part of the Gospel of the Kingdom/Grace.
And Jesus ended his ministry by inspiring Heb. 7:11-10:1 to point us in the right direction when trying to understand how the OT and NT jibe/should be harmonized, which is the way/direction Jesus and the Apostles went/commented and the way we should, too.