How do I get rid of this stain? Tried everything including bleach

Is it rust .I would try a pumice stone . Flush turn water off .then try the stone .

Use 2-3 antacid tablets, drop in, wait 20 minuted and then brush and flush.

there are cleaners for rust that will take this off but you would have to drain the bowl first- all the big box stores have rust removers

What works best for me is to turn off your water to the tank and use a plunger to get as much water out of your bowl as possible. Then use a product called "Whink" rust remover and let it set for a bit. You may need to do this more than once if the rust stain is thick and has been there a while.

looks like limescale to me

try circle out, can buy them at home depot and lowes, looks like a piece of screen, works wonders.

Pumice Stone

it is rust.....pour white vinegar followed by baking soda in the tank and the toilet allowing it to sit overnight, plain coke will remove rust

It is definitely rust - probably won't come out unless you can sand it off with a wire brush or steel wool.

When we moved into a home I thought this was a stain but it turned out to be where the previous owners used a metal "snake" to clear the drain and scratched the porcelain.

Here's a post that might help - https://chascrazycreations.com/how-to-clean-your-toilet-from-top-to-bottom/