Non-compete clauses in employee contracts is an issue for intern/co-op student jobs. For example, Amazon had students sign one that said 18 months, which if the student worked at Amazon before their senior year would impact what jobs they could take once they graduated. These agreements come under state law and so their enforceability will vary depending upon the state (and become more complicated if the agreement is signed in a different state than the person ends up working.)
In CS, contracts very often have an intellectual property clause, where anything you work on during their employment belongs to the company. So no working on the next big tech thing in your garage at night after leaving the office.
I would see lots of red flags for an employer pressuring a soon to be college grad into signing a contract. Companies who make offers to interns often put a time limit on the offer (one company I know of will pay a bonus if the student signs up early). But these time limits are frequently negotiable if the company really wants that student.
Good Luck to your child finding the right job. The CS hiring process can be trying (many rounds of interviewing and skills tests).