Here's what we can infer based on the story and its context:
* Medieval Period: The story takes place during the medieval period, which dictates the general style of clothing. We can expect to see robes, tunics, and gowns, all heavily influenced by the fashions of the time.
* Royal Characters: The King, Queen, and Prince (Don Juan) would wear luxurious clothing befitting their status. Think rich fabrics like velvet, silk, and brocade, ornate embroidery, and perhaps even jewels.
* The Peasant Characters: Characters like the three brothers would wear simpler clothing made of coarser materials. They would be practical and functional, emphasizing movement and ease of use.
* The Adarna Bird: The Adarna bird, being a magical creature, could be depicted in a multitude of ways. It could wear feathers with vibrant and magical colors, or it could be designed more realistically, with feathers that reflect light and create beautiful patterns.
Ultimately, how the characters are dressed depends on the artist's interpretation and the particular version of the story being adapted.
However, some artists have depicted Ibong Adarna characters in various ways. You could search for illustrations or adaptations to find specific examples.