Would it be possible for an alien race to have cat, dog and bunny features? by features I mean ears, noses fur etc. And also be very short, only about 1-3 feet. What evolutionary factors might cause it to occur naturally? Assuming they come from a planet like Earth. And most importantly they are very intelligent, comparable to humans.
If you asked me if a genetically modified terrestrial race can have cat-, dog- and bunny-like features, I'd say yes, probably.
Convergent evolution is a thing, even among completely different species, so add a bit of near-future bioengineering and voilá.
But an alien race... I don't know, that may be a bit too much. The Alien race need to be carbon-based, possess body mirrorring, fur-like external structures... the list of necessary coincidences is simply too high.
But then, space is big. Like, really big.
Bigger ears mean better hearing, it's structural thing. Fur keeps bodies warm, so it would be found on endothermic species. Smaller species require less food, find it easier to hide, etc. Every trait an animal has is theoretically survival positive so one might theorize it could evolve independently in a non-terran species.
Certainly, an alien might look like a bunny or cat, but that might be human eyes and brains trying to make sense of what they are seeing. When we see things that are unfamiliar, we try to relate them to familiar things. That's why we see a "face" on the moon, or in a gnarled tree.
If someone saw an alien, their brain might say "what do I know of that looks closest to this?" and come up with "bunny?" "cat?" because it has long ears but moves more like a cat. Even once they know it to be an alien, they might still think it looks kind of like a cat or rabbit, and might react accordingly.
Your question needs a bit more detail. Why do you want the alien to look like a bunny / cat / dog? What is the intended result? I think if we knew that we'd have an easier time helping you.