Here are some features and design 

1. **Frozen and Sofia Characters**: Include embroidered or printed designs of popular characters like Elsa and Sofia.

2. **Color Palette**: Use a color palette inspired by Frozen and Sofia, such as icy blues, soft purples, and hints of silver or gold for a magical touch.

3. **Materials**: Opt for durable materials like canvas or polyester to ensure the bag is sturdy and easy to clean.

4. **Size and Compartments**: Given the dimensions (14" height x 10" width x 4.5" depth), design the bag with a main compartment for books and folders, smaller compartments for stationery, and side pockets for water bottles or snacks.

5. **Comfortable Straps**: Ensure the shoulder straps are padded and adjustable for comfort, especially for young children carrying books and supplies.

6. **Inner Lining**: Line the inside of the bag with a coordinating fabric featuring more character prints or patterns from the themes.