BG 3.21
यद्यदाचरति श्रेष्ठस्तत्तदेवेतरो जनः। स यत्प्रमाणं कुरुते लोकस्तदनुवर्तते
yad yad ācharati śhreṣhṭhas tat tad evetaro janaḥ sa yat pramāṇaṁ kurute lokas tad anuvartate
For whatever a great man does, others imitate; people conform to the standard he has set.
Translated by Shri Purohit Swami
Whatever a great man does, others also do; whatever he establishes as the standard, the world follows.
Translated by Swami Sivananda
Word meanings (from the gita/gita dataset)
yat yat—whatever; ācharati—does; śhreṣhṭhaḥ—the best; tat tat—that (alone); eva—certainly; itaraḥ—common; janaḥ—people; saḥ—they; yat—whichever; pramāṇam—standard; kurute—perform; lokaḥ—world; tat—that; anuvartate—pursues