When we doubled the dimensions of Carlos the Scale Factor is 2. When we find the area you use the scale factor twice. You also need to do it twice because you need to have a length and a width. The perimeter is used once the area used the scale factor twice which made it 4 times bigger.
When we tripled the dimensions of Carlos the Scale Factor is 3. We used the scale factor twice for the length and the width of Carlos. The perimeter was used once and the area was 9 times bigger. The perimeter was 12 and it was originally 8, and the area was originally 1, but ended up with 9.