Dogs with a chest circumference of 21-27 inches (53-69 cm) and weighing 20-30 pounds (9-14 kg) are typically considered medium to large small breed dogs. Here are some examples of breeds that may fall within this size range:

1. Beagle

2. French Bulldog

3. Boston Terrier

4. Cocker Spaniel

5. Collie (medium size)

6. Corgi (Pembroke Welsh)

7. Dachshund (standard size)

8. English Springer Spaniel

9. Harrier

10. Miniature Australian Shepherd

11. Miniature Schnauzer

12. Poodle (Miniature)

13. Shetland Sheepdog (Sheltie)

14. Whippet (smaller individuals)

These dogs are often:

- Friendly and affectionate - Energetic and playful - Intelligent and trainable - Loyal and social

- Active, but may require less exercise than larger breeds - Suitable for apartment living or homes with small yards

Some characteristics of dogs in this size range include:

- Compact, athletic buildm- Short to medium-length coats - Floppy ears and sweet expressions - Curious and adventurous personalities - Generally good with children and other pets

Remember, individual dogs can vary depending on their breed, lineage, and personal characteristics.