That depends upon which country you live in.
Olive Garden does have a few branches in the UK serving overpriced mediocre food, but the UK branches certainly don’t stand out as serving huge portions.
It’s pretty much only in the Americas that it’s usual to get served enormous portions with the expectation that diners will not manage to finish. As a result, diners, particularly in the USA, tend to judge restaurants by quantity and not quality. Much as I love the USA, I always look forward to returning to the much better quality and variety I get in Europe and the UK.
So no, outside North, and to an extent South, America, portions tend to be sufficient instead of gargantuan. Although sadly the UK is definitely moving towards supersizing and quality or quantity and I’ve started to see signs of that throughout Germany as well.