The NT is the fulfillment of the OT.The NT is in the OT.
2pet 3This is now, beloved, the second letter I am writing to you in which I am stirring up your sincere mind by way of reminder, 2 that you should remember the words spoken beforehand by the holy prophets and the commandment of the Lord and Savior spoken by your apostles.
luke 24Now He said to them, "These are My words which I spoke to you while I was still with you, that all things which are written about Me in the Law of Moses and the Prophets and the Psalms must be fulfilled." 45 Then He opened their minds to understand the Scriptures, -( OT )46 and He said to them, "Thus it is written, that the Christ[19][I.e. Messiah] would suffer and rise again from the dead the third day, 47 and that repentance for forgiveness of sins would be proclaimed in His name to all the nations, beginning from Jerusalem. 48 "You are witnesses of these things
Hebrews and matthew always refer to the OT and its good to have 2 bibles so you can reference it in the OT , and get a headstart this way into reading that part of the bible.When reading Revelation, you will find numerous refs to the OT, especially Daniel and Ezekiel.