How did Jesus fulfill the prophecies of the Old Testament?

To understand the prophecies of the Old Testament about Christ, it is necessary that you have already been convinced of His deeds. The apostles, for example, only began to see Christ clearly in the Old Testament after witnessing His miracles and resurrection. Additionally, they also received the gifts of the Holy Spirit (such as the gift of performing miracles in the name of Jesus Christ). Therefore, after witnessing all of this, they, looking at the Old Testament, saw Christ. Thus, before trying to understand the messianic prophecies, it is necessary to seek reliability in the Gospel and in the apostles' account of Christ. By trusting their account, you can then understand the prophecies.

Below is verse 37 and 38 from the Gospel of John:

"37 If I am not doing my Father's work, there is no need to believe me; 38 but if I am doing it, then even if you refuse to believe in me, at least believe in the work I do; then you will know for certain that the Father is in me and I am in the Father."

Additionally, regarding the term "fulfill" used by Saint Matthew, it can be used in two ways: 1- To completely fulfill something 2- To complete something that was incomplete

Choose to read the text with the second meaning, and even though some passages refer to Israel, consider that Christ is the King of Israel (and of the whole world), and a king represents his people, which can help in the interpretation.

Anyway, that’s it.

Dominus Vobiscum