Function is_rich 

pub fn is_rich() -> bool

Whether decorative UI may animate (bars/spinners) and color may be emitted.

Plain mode (the inverse) is selected when stdout is not a terminal — piped, redirected, or running under CI — or when the operator has set NO_COLOR (https://no-color.org/). In plain mode we emit terse, uncolored status lines and never draw a spinner or bar.