Read:
https://help.cbp.gov/app/answers/detail/a_id/268/~/children---child-traveling-with-one-parent-or-someone-who-is-not-a-parent-or
https://help.cbp.gov/app/answers/detail/a_id/449/~/traveling-with-children---minors-under-18-years-of-age-traveling-to-another
Also contact the airlines if no one accompanies with the child to see whether they provide such service.
https://help.cbp.gov/app/answers/detail/a_id/268/~/children---child-traveling-with-one-parent-or-someone-who-is-not-a-parent-or
https://help.cbp.gov/app/answers/detail/a_id/449/~/traveling-with-children---minors-under-18-years-of-age-traveling-to-another
Also contact the airlines if no one accompanies with the child to see whether they provide such service.
