I have a coffee shop with 2x2 white ceramic tiles that badly need a refresh
mr. Clean eraser
I just use baking soda and vinegar. If there's grease or grime, I sprinkle baking soda on a sponge and scrub. Otherwise, use diluted vinegar.
If particularly grimy and the other ideas don't work, Lysol Lime & Rust Remover Toilet Bowl cleaner, comes in a black squirt bottle. Scrub with Scrub Daddy or Mr. Clean Magic Eraser. If stubborn, use a scouring stick to scrub.
baking soda and bleach mixture left overnight.