I want to know how puppies should sleep.Should they be confined to a small carrier to sleep in, or a large box?

I am a firm believer in a small crate. They meet the dog's instinctive need for a protective den. I never had any problems with a small puppy in a large crate, but many people report small crates working better. Best thing might be to buy one big enough for the adult and block off part of it. JRT's may not be as destructive as Labs would be loose in the house, but the crate still helps. They are great for travel, especially if you fly. For more on crates and other information that may help see https://www.askmehelpdesk.com/dogs/information-articles-our-dogs-expert-labman-53153.html#post251802