John, Jesus’ cousin, was chosen before he was even born to prepare the way for Jesus.
An angel had already told Zechariah (John’s father), that the as-yet unconceived baby would:
Luke 1:16-17 And he will turn many of the children of Israel to the Lord their God. He will also go before Him in the spirit and power of Elijah, ‘to turn the hearts of the fathers to the children,’ and the disobedient to the wisdom of the just, to make ready a people prepared for the Lord.
This made John the metaphorical return of Elijah that people were waiting for.
And after the child was circumcised, Zechariah prophesied the role he would play:
Luke 1:76-79 And you, child, will be called the prophet of the Highest;
For you will go before the face of the Lord to prepare His ways,
To give knowledge of salvation to His people
By the remission of their sins,
Through the tender mercy of our God,
With which the Dayspring from on high has visited us;
To give light to those who sit in darkness and the shadow of death,
To guide our feet into the way of peace.”