"Elephants are large and cats are little."
Translation:Les éléphants sont grands et les chats sont petits.
I think you made other mistakes there (plural vs singular), you are talking about les so you should have said les Français sont fous (French men and women) or les Françaises sont fous (French women). Since I am a learner just like you, I don't know how to use puer yet and I don't want to give an incorrect explanation. I hope someone with a better understanding of French can explain that.
Les éléphants, elephants is a masculine plural noun so you need to use ''grands'' (masculine, plural).
If you listen carefully the final t in petit is not pronounced - so petit is used to describe a masculine noun. If the "t" is pronounced - petite is used to describe a feminine noun. So the noun is chats (masculine, plural) Les chats sont petits.