they could. in the US, the student may be eligible for a 504 plan to cover it.
CPS does not help get excused absences. CPS might step in and investigate the family for neglect.
Yes the parent would need to agree to the 504 plan. The plan could simply stay student is exempt from the standard attendance policy provided absences are medically verified and explain how student will be allowed to make up work (ie teacher will email assignments to parent/student will turn in assignments within 1 week). If a parent refuses to agree to that, it indicates some type of abuse at home. 504 plans are for students in regular ed who only need accommodations such as extra absences.
Schools typically have an allowance for 'excused absences, but if it is a lot more than usual, doctors notes alone may not be sufficient.
if the student/family are taken to court for truancy, a judge could rule if the absences are excessive or not.
If the only issue is absences due to medical reasons, a 504 plan may be sufficient. CPS could potentially place a child in foster care for educational neglect.