Does drinking excess water at night before going to bed enlarge prostrate nd harm kidney?

NO. Drink when you are thirsty. But prostate enlargement can damage kidney.

Drink enough water daily, not necessarily at bed time, so that your urine is mostly colorless. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get HPV and Covid vaccines. Wish you good health!