I soo do not want to offend anyone with this post, and I truly believe that all puppies are cute, and adorable, and potentially great dogs, given the proper upbringing, whether they're poodles or pit bulls, but a Cavachon is not a breed of dog, but rather a mixed breed, between a Cavalier King Charles Spaniel, and a Bichon Frise. Since no reputable breeder of either of these breeds would intentionally mix them, when you buy a Cavachon, you're buying a pup that was bred purely for monetary, designer dog reasons, more than likely in a puppy mill. If you don't know what a puppy mill is, google it.
So the answer is, there is no answer, a Cavachon puppy could grow up to weigh 5 lbs., or 25, it could be long legged and short bodied, or short legged and long bodied, it could be easily trained, or it could be stubborn as a mule. It could be smart as a whip or dumb as a box of rocks. It could have the tempement of an angel, or a miniature Cujo. There is no standard for them, the people who breed them are only interested in taking your money. If you want an adorable little mutt,which is exactly what Cavachons are,I suggest you go to your local pound or shelter and save a life, rather than support a terribly cruel industry, many of whose victims will end up there anyway, either to be (hopefully) adopted, or (more likely) euthanised. And it will only cost you a modest adoption fee, instead of an outrageous purchase price.