That’s funny. John the Baptist was preaching repentance using Isaiah’s prophecy as a witness.
Again, we are His wheat and He will burn up the wheat chaff.
you who do not know what will happen tomorrow, what your life will be like . For you are a smoky vapor that appears for a short time and then disappears.
James 4:14 -
https://www.biblegateway.com/passage?search=James 4:14&version=LEB
His body didn’t visibly change that day, but it will at His second coming when He threshes His wheat and burns up the chaff.
Purified is the Biblical word actually, but what of the things in their flesh that needed cleansing and purging? That’s the refiner’s fire to come on the Day of the Lord! Baptism of the Holy Spirit doesn’t actually clean the flesh, only the soul.
And also, corresponding to this, baptism now saves you, not the removal of dirt from the flesh, but an appeal to God for a good conscience through the resurrection of Jesus Christ,
1 Peter 3:21 -
https://www.biblegateway.com/passage?search=1 Peter 3:21&version=LEB
Yes he was changed on the inside by God that day. Reborn from above. And his mind was being changed after that day but not his body (which was still mortal). That’s a change yet to come when the Lord returns to thresh His wheat and burn up the chaff (which is the outer covering of the wheat).
[Christ] who will transform our lowly body that it may be conformed to His glorious body, according to the working by which He is able even to subdue all things to Himself.
Philippians 3:21 -
https://www.biblegateway.com/passage?search=Philippians 3:21&version=NKJV
After baptism with the Holy Spirit, he stood boldly against those very ones who murdered Christ with powerful preaching of the Gospel though not being able to see Christ because Christ had not yet returned to gather His wheat and burn up the chaff as John the Baptist predicted.
Not only was there no wheat chaff burnt up at Pentecost, Peter (one of His wheat) wasn’t gathered into His barn that day either.
John responded, saying to everyone, “ I am baptizing you with water, but the One more powerful than me is coming, of Whom I am not fit to untie the strap of His sandals. He will baptize you with the Holy Spirit and fire — Whose winnowing-tool is in His hand so as to clean-out His threshing floor and gather the wheat into His barn; but He will burn up the chaff with an inextinguishable fire”.
Luke 3:16-17 -
https://www.biblegateway.com/passage?search=Luke 3:16-17&version=DLNT
Oh, BTW, John said the one more powerful than me is coming. Hadn’t Jesus already come the first time when John prophecies His coming?