Cornelius in Acts 10 was a regenerate man since he had the fear of the Lord, he was also be considered wise, the beginning of wisdom, which no man has by nature
Prov 1:7
The fear of the Lord is the beginning of knowledge: but fools despise wisdom and instruction.
And Cornelius was a Just/Justified Man even before he heard and believed the Gospel Peter preached to him.
Acts 10 22 And they said, Cornelius the centurion, a just/justified man, and one that feareth God, and of good report among all the nation of the Jews, was warned from God by an holy angel to send for thee into his house, and to hear words of thee.
He was already accepted of God and doing works of righteousness Acts 10:34
But in every nation he that feareth him, and worketh righteousness, is accepted with him.
Only a regenerate person can be accepted of God and be doing works of righteousness.
That cannot happen with man by nature Rom 3:10,12
As it is written, There is none righteous, no, not one:
They are all gone out of the way, they are together become unprofitable; there is none that doeth good, no, not one.