Hey Aniket you can easily complete Varanasi trip in two to three days, Sarnath , Assighat, Dashshwamedh Ghat, Kashi Vishwanath temple, evening Ganga Aarti at Dashshwamedh Ghat , Vishwanath temple in BHU campus, evening boat ride at ghats are the most popular destinations to cover which you can easily do in two to three days.