Jesus knew from a very young age that He was going to die on The Cross.
He certainly know it when He was pre-incarnate as "the Word was God"... Jn1.
However, during His 3.5 years of earthly ministry dealing with the Jews.......He didnt tell them about His Cross, or Him dying on it.
Later, after His Resurrection.. when Jesus was back in Heaven.......He called Paul into the Ministry to bring "the preaching of the Cross" to the World, but mostly to the Gentiles, as Jesus's Cross began "the time of the Gentiles".
So, "in the time of the Gentiles" with Paul being the "Apostle TO the Gentiles".. He brought us what he refers to 3x in the NT, as "MY Gospel"..
Jesus never preached this when He was on earth... And Paul preached only "Christ Crucified"., and this is the Gospel that the "church" is to preach to the world.