熠熠生辉 is high-register, common in journalism, advertising and literary writing — 'the city's lights shine brilliantly', 'the diamond sparkles', 'a rising star shines'.
熠 alone (Xinhua:
鲜明，
光耀) means 'glittering/dazzling'; reduplicated
熠熠 intensifies the shimmer;
生辉 = 'give off radiance'. Don't apply to plain practical light — reserve for things meant to dazzle.
