Matthew 26:27-28 was a record of what was said to Jews who were still living under the Law.
Then he took a cup, and when he had given thanks, he gave it to them, saying,
“Drink from it, all of you. This is my blood of the covenant, which is poured out
for many for the forgiveness of sins." Matthew 26:27-28
And...
Peter in Acts 2:38?
At that point Peter had no New Testament doctrine yet to think with.
For he still thought and acted, as he had as a Jew, before the cross took place.
We see that later on Peter finally recalling the words of the risen Jesu that Jesus spoke in Acts 1:5.
That was when Peter finally realized that water baptism was to be replaced by Spirit baptism.
Soon after Jesus was risen... (Not yet ascended to heaven) Jesus spoke with the disciples.
On one occasion, while he was eating with them, he gave them this command:
“Do not leave Jerusalem, but wait for the gift my Father promised, which you
have heard me speak about. For John baptized with water, but in a few days
you will be baptized with the Holy Spirit.” Acts 1:4-5
Did Peter remember those words in when he spoke in Acts 2:38? ...... NO!
Did not remember until all the way over in Acts 11:16!
That is when Peter finally recalled those words of Jesus!
Then causing Peter to realize that the old way - water baptism - was to now being replaced by Spirit baptism!
“As I began to speak, the Holy Spirit came on them as he had come on us at the beginning.
Then I remembered what the Lord had said: ‘John baptized with water, but you will be
baptized with the Holy Spirit.’ Acts 11:15-16
Missing these details is why so many Christians are failing to understand, what they do have become the traditions of man, not God's way.
Just read it and think.