My landlord put in a lock box on the thermostat. And left the temperature at 63 degrees. What is the law in pa about this.

Such laws are usually on a local basis, either the county or municipality level. I found this article (Proposed ordinance would require Lopatcong Twp. landlords to meet heat requirements year-round | lehighvalleylive.com) that refers to a proposed ordinance but no indication if it was passed.

My research indicates that 65-68 is the norm. I would check with your local housing department.

I would suggest that you contact the local building department