You are referring to 1 Peter 3: 18-20. There is debate within Christian circles as to what this passage means. For example, some think it was Christ preaching "in the Spirit" through Noah during the pre-flood days. Others think it is demons that Christ preached to in hell while He was in the grave declaring His victory at the cross. And some, like you, think it was humans He spoke too.
I'm not going to spend the next 5 days debating with you over which one is right. I'm not even going to reveal to you my opinion on this passage that way I can make sure I avoid arguing with you. I will say this though:
Hebrews 9: 27, "It is given to man once to die and then the judgment"
Matthew 25: 1-13, The parable of the foolish virgins not being ready and shut out of the kingdom.
Luke 16: 19-31, "...If they do not hear Moses and the prophets, neither will they be persuaded though one rise from the dead."
I could give a ton more Scriptures. The Bible teaches from start to finish that if you don't accept Christ,
in this life, you perish. You don't get a "second chance" in hell.
Your suggestion goes against everything the Bible teaches and is built on an ambiguous passage with many possible interpretations. That is a recipe for winding up with false doctrine.
Like I said before, I don't think it is helpful to discuss this topic further with you. You have your belief in what you think the Scripture says on this subject, just like I do. I try to build my doctrines off clear verses not ambiguous ones.
Nevertheless, I wish you well in your search for truth in the Scriptures and Lord willing we may have further discussions on here.
God bless you and thank you for the conversation.