The RENIEC website has a contact facility. You could try writing to them to see if there is any way to get the information you are after. If you don't speak Spanish, write in English. They probably have someone in the office who can handle an inquiry in English as long as you use simple, straight forward sentences. Make it clear that you are writing from abroad, that you are not a Peruvian citizen and that you are seeking the information for family history purposes.
https://www.reniec.gob.pe/portal/Principal.htmat the bottom of the home page: Contáctenos
in the far left column: CONSULTAS RENIEC
in the form:
Asunto: Registros Civiles
Escriba Aquí: write out your question in the box
Nombre y Apellido: your full name
email: your email adress
Doc. Identidad: leave it blank
Teléfono: your phone #
Alternatively, if you happen to live near a Peruvian embassy or consulate, you could make a personal visit and ask them how to proceed.
I once had occasion to make inquiries at the Chilean embassy here in Quito on behalf of another RootsChatter. The embassy personnel were extremely helpful, to the extent of hauling out their daily log books from the 1940s in an effort to find information on the person of interest. Unfortunately, we didn't find any record of him though they made every effort to help.