The hex color #210cf9 is a dark color. The web-safe version is Hex
#3300FF. A complementary color is
#DEF306. The grayscale version is
#626262. A 20% lighter version of the original color is
#543FFF, and Hex
#0000C6 is the 20% darker color. If the color is saturated by 10%, you get
#1B03FF. If the color is desaturated by 10%, the color
#2815EA is obtained.