The context of these verses seem to be talking about the demonstration of the Spirit and the power concerning Jesus Christ and him crucified.
I don't think these have to do with the signs and wonders that were performed by him in other passages.
These new believers had so many problems going on in their congregation that had been communicated to Paul from the household of Chloe. There were divisions, gross immortality, lawsuits between believers, and many others that he addressed in the letter.
Many of these members were recently converted from pagan practices and they were having difficulty in adjusting breaking with the past. The word of the cross is the power for them to get on with their new lives.
To fix these problems they needed more than empty words spoken out of man's inflated wisdom. What was needed is a demonstration of the Spirit and power.
Their faith should not rest on the wisdom of men but on the message backed by the power of the Spirit of God.
Paul determined to know nothing among them except Jesus Christ and him crucified. 1 Corinthians 2:2
They had already seen that power in their own lives as their testimony concerning Christ was confirmed in them. 1 Corinthians 1:6
always thank my God for you because of the grace He has given you in Christ Jesus. 5For in Him you have been enriched in every way, in all speech and all knowledge, 6because our testimony about Christ was confirmed in you.
For the word of the cross is the power of God.
For Christ did not send me to baptize, but to preach the gospel, not with words of wisdom, lest the cross of Christ be emptied of its power,
For the message of the cross is foolishness to those who are perishing, but to us who are being saved it is the power of God. 1 Corinthians 1:18
The question you brought forth concerning 1 Corinthians 19 and 20.
There were some in the Corinthian's midst who sounded very eloquent with their words that didn't seem to have any power associated in changing lives with their words.
First Corinthians 4:21 is very telling of these people who were teaching them. Sounds like they had a rod on their backs trying to get them in shape. It certainly seems like just the opposite happened.
What do you desire? Shall I come to you with a rod or with love and a spirit of gentleness?
1 Corinthians 4:21
Which is more powerful??