It is a thing.
When a child has been raised in a Christian home by Christian Parents and grows up and knows enough to accurately explain and receive Salvation from Jesus...
That's called confirmation.
Sanctification isn't in scripture either..."sanctify" is in some translations but sanctification is not.
Matthew 16:13 When Jesus came into the coasts of Caesarea Philippi, he asked his disciples, saying, Whom do men say that I the Son of man am? 14 And they said, Some say that thou art John the Baptist: some, Elias; and others, Jeremias, or one of the prophets. 15 He saith unto them, But whom say ye that I am? 16 And Simon Peter answered and said, Thou art the Christ, the Son of the living God. 17 And Jesus answered and said unto him, Blessed art thou, Simon Barjona: for flesh and blood hath not revealed it unto thee, but my Father which is in heaven.
This is confirmation as Peter was asked a question and God gave Peter confirmation that Jesus is the Son of God.
2 Timothy 2:19 Nevertheless the foundation of God standeth sure, having this seal, The Lord knoweth them that are his. And, Let every one that nameth the name of Christ depart from iniquity. 20 But in a great house there are not only vessels of gold and of silver, but also of wood and of earth; and some to honour, and some to dishonour. 21 If a man therefore purge himself from these, he shall be a vessel unto honour, sanctified, and meet for the master's use, and prepared unto every good work.
Notice the word sanctified in vs. 21 as this means set apart and made holy by God once we purge ourselves of sin (repent).
Sanctification as used in the new covenant is HAGIOSMOS (Greek word) and means basically set apart in the sense of being set apart from all else and dedicated for God's use. This is a work of grace at salvation sets the believer apart as separate from and holy unto God