What is the biblical basis for “the Sinner’s Prayer” and do Protestants believe that saying the prayer make one a Christian?

I came across ***a similar question*** asking about the Protestant view that when you first believe on Jesus Christ you become a Born Again Christian. Here is the link to the question: https://christianity.stackexchange.com/questions/50206/how-did-the-born-again-teaching-be-associated-with-one-first-believing-in-jesus/72288#72288 Please note that I am ***not*** asking about how a Christian is born-again. I am asking about the claim that Protestants think if you say "the Sinner’s Prayer” then you become a Christian. I’ve been a Protestant for a long time but have never subscribed to any notion that simply repeating some words will automatically make a person a Christian. That is clearly unbiblical because there must be evidence of a life transformed by the Holy Spirit at work in the believer. >"Therefore, if anyone is in Christ, he is a new creation: the old has gone, the new has come!" (2 Corinthians 5:17). My understanding is that it is the Holy Spirit who convicts sinners of their need to repent and turn, in faith, to what God has done, in Christ Jesus, and seek forgiveness. A “Prayer of Repentance” might better express what sinners need to do in order to be saved. It seems to me that there are some commonly held misconceptions about this “Sinner’s Prayer”. My question is therefore aimed at Protestants in order to give them an opportunity to clear up any misunderstandings and to show, from the Bible, what it is that makes a person a Christian.