this requires a careful response:
the OT is truly Scripture, and it communicates, for the most part, a literary treatment of the beginning ages of human history that prepared the way for the Coming of Our Savior. It includes the preeminent stages (Creation, Fall, Flood, Babel, Abraham) as well as the stages of the Jews (Egypt, Exodus, Prophets, Exile, Restoration, OT Antichrist Antiochus).
The OT is essential to Catholic doctrine, for God NECESSARILY had to, in order to have, in the end, the greatest possible spiritual good, intervene and guide a Covenant People to prefigure the fulfillment in Christ.
I like to use Jack Nicholson: “you can’t HAAANDLE the truth.” (jeff Cavins coined that in his Bible study.

) Humanity had to be PREPARED to receive the full bug of Divine Revelation and Grace in Catholicism. That required stages of intervention and development to gradually move humanity into a condition able to receive the fullness of truth.
BUT, it necessarily means that much of the Old Jewish Law was merely a CEREMONIAL and RITUALISTIC foreshadowing of things in Christ, and meant to set the Jewish people apart (the teach the lesson of the specialness of fidelity and holiness), so that much of these minor laws and rituals are no longer binding, and have been fulfilled, as it were, in the rituals and love of the New Covenant.
So there is a yes and no here. We no longer wash our sheets and cups in a special way, kill two pigeons and Lambs, and have relations at strict intervals around menstruation (although NFP is strikingly similar!

). But, the moral essence of the Ten Commandments, and the Sermont on the Mount do form a basis as the NT commandments, the commandments that are summarized as "“Love God with all that is in you, and your neighbor as yourself.”
I don’t know if this helps, strywnd?