Visit floating market and Buddha Temple's during the day time Do Clubbing at Night or Nana Plaza If you want to 🤫 or you can Do Night shopping in the street. Next day you can go to MBK mall also it's an Huge mall for Shopping
Visit those fancy rooftop bars :- I suggest Above eleven , Sukhmvit 11
If you haven’t taken river cruise then Chao Pyara river cruise can be done You can sit at River front of bangkok Or just do shopping at Mall
If you like to visit temple then you can cover maximum temple in a day and Bangkok is always famous for it's cheap and awesome shopping culture. so you can do shopping as well. when I was in Bangkok I had spent 2 days just for shopping and realized still need one more day.