Brazil dwarfs Mexico: about 8,499,400 km² km² against 1,962,279 km² km². At true size Brazil is about 4.3× larger — the whole of Mexico fits into Brazil roughly 4 times.
Brazil sits in South America, Mexico in North America. On the old Mercator map the latitude gap distorted how large each felt beside the other; at true size the answer is simply 4.3×.
The old Mercator map treated both about equally (1× vs 1.2× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
Mexico fits 4× into Brazil.