If an employer has a biweekly payroll and it has a regular pay out date of- let's say Wednesday (day of the week is unimportant) and that date is a holiday in which the business is closed, is there any federal or state law that states an employer must issue the payroll on the day BEFORE the holiday (or after the holiday)? Employer is in Iowa

No, Iowa has no such requirement. Very few states do. Iowa law requires only that payday be no later than 12 days following the end of the pay period, excluding holidays and weekends.