You will need: vinegar, baking soda, a brush, gloves, a spray bottle.

Pour 3/4 cup of baking soda into the toilet.
Pour 2 glasses of vinegar.
A chemical reaction will be activated, almost “effervescent”.
Fill the spray bottle with vinegar and spray it everywhere in the toilet, especially on the areas where the baking soda hasn’t yet worked.
Use the brush to scrub the entire toilet, leaving the baking soda and vinegar to act for a few minutes (at least 2-3).
The toilet will be as good as new. It is an economical, ecological and very effective solution, not to mention the absolute lack of chemicals.