EternalFire
If the answer you are looking for is forgiveness of sins, see my response below.
Luke 24:44-48 ESV
Then he said to them, “These are my words that I spoke to you while I was still with you, that everything written about me in the Law of Moses and the Prophets and the Psalms must be fulfilled.” Then he opened their minds to understand the Scriptures, and said to them, ”Thus it is written, that the Christ should suffer and on the third day rise from the dead, and that repentance for the forgiveness of sins should be proclaimed in his name to all nations, beginning from Jerusalem. You are the witnesses of these things.
Notice that Jesus tells them that repentance for the forgiveness of sins should be proclaimed, not baptism for the forgiveness of sins.
So, in verses like Acts 2:38, did Peter decide to add baptism in water to what Jesus had commanded him to proclaim. The fact that verses like Acts 3:19 and Acts 10:43 repeat essentially the same concept, but leave out baptism lead me to think he did not intend to add anything to what Jesus told him.
in my post #73 I made the case that the baptism in Acts 2:38 is simply immersion into forgiveness of sins, meaning into the new covenant. The Greek words eis aphesin hamartion are the same in both Luke 24:47 and Acts 2:38. If you read this as into forgiveness of sins then Acts 2:38 looks something like this.
Acts 2:38
And Peter said to them, “Repent (change your mind) and be immersed every one of you on the authority of Jesus Christ into the forgiveness of your sins, and you will receive the gift of the Holy Spirit.
So, forgiveness of sins was entered upon repentance, and Luke 24:47, Acts 2:38, Acts 3:19, and Acts 10:43 all say the same thing.