Answer:
It is three times as large
Step-by-step explanation:
If a ration is also a fraction, and your wording is correct than an enlargement of 1:3 where 1 is the original shape would suggest that the 3 would be that same original shape, be enlarged in terms of 3 compares to 1 so a 300% enlargement.
if the original rectangle has a 16 cm perimeter, than the new rectangle has a 48 cm perimeter.