How can I clean my white porcelain sink that has scuff marks from pots

Try Bon Ami

barkeepers friend scouring powder---if not in local stores, available from amazon it's magical!

Have you tried Barkeepers friend?

Im impressed by all the cleaning problems it solves, it may resolve your scuff stains.

”Trusted by homeowners, hobbyists, musicians, and professional cleaners worldwide, Bar Keepers Friend superior hard surface cleansers tackle rust, mineral deposits, baked-on food, and other tough stains with gentle, bleach-free formulations. Available wherever household cleaning products are sold, Bar Keepers Friend makes industrial-strength cleaning safe, quick, and easy.”

https://www.barkeepersfriend.com/

Use Comet or Bab-o scouring powder and it’ll be like new.

Bar Keepers Friend is a great cleaner and then use car wax on it, buff it out.

Bleach

Bar Keepers Friend will work. Sprinkle a little bit on a wet sponge or rag & rub spots with it. Rinse well.