What we do not know is if Jesus pointed to Himself when He said "upon this rock". However, we can discern that the "rock" Jesus was referring to is Peter's proclamation of faith in Christ revealed to Peter by the grace of God.
Since all the Apostles were Jews they would have been familiar with the OT prophecies concerning the coming Messiah. They would also have understood the "metaphor" of Jesus referring to a "rock".
Now since you have posted the Greek and the English translation how do you substantiate your claim “Petros”, which is masculine, and "petra", which is feminine can agree grammatically? On other threads where we bring this up you insist that Jesus spoke Aramaic and “Cephas” is Peter’s name. Since Hebrew only has on word for “rock” the supposed Aramaic original of Matthew would have had “Cephas” in both places. But, since Hebrew and Aramaic are similar the Apostles would have immediately associated the “rock” Jesus was going to build His Church on was Himself, the Messiah.
Thank you tuppence that was a excellent post.