Peru dwarfs South America: about 1,296,279 km² km² against 17,840,000 km² km². At true size Peru is about 13.8× larger — the whole of South America fits into Peru roughly 13 times.
The old Mercator map treated both about equally (1× vs 1× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
Peru fits 13× into South America.