绚丽 (xuànlì) holds a strong literary and artistic weight in Chinese culture. It's a word you're more likely to find in poetry, literature, and art criticism than in everyday casual conversation. It taps into a traditional aesthetic that values intricacy, vibrancy, and richness of color, as seen in imperial dragon robes, detailed silk paintings, and ornate temple decorations. A helpful comparison for Western learners is to contrast it with “splendid” or “grand.” A vast, minimalist modern art museum might be described as “grand,” but not 绚丽 (xuànlì). A massive, ancient sequoia tree is “majestic,” but not 绚丽 (xuànlì). However, the same forest in peak autumn foliage, with a riot of reds, oranges, and yellows, would be perfectly described as 绚丽 (xuànlì). The term almost always implies a multiplicity of brilliant colors that creates a magnificent visual effect. It values vibrant complexity over simple, monolithic beauty.
绚丽 (xuànlì) is a fairly formal and descriptive word. It's used when you want to add a touch of literary flair or emphasize the spectacular nature of something's colors.
It is generally not used to describe people in a casual context. Calling a person 绚丽 (xuànlì) would sound strange, implying they are dressed in an outrageously colorful and elaborate costume, like a performer.
The most common pitfall for learners is confusing 绚丽 (xuànlì) with more general words for “beautiful.”