Is there some way to make my toilet bowl look cleaner?

baking soda and white vinegar in the tank and toilet allowing g to sit overnight, pumice stone,koolaid,plaain coke

It does look like the porcelain at the bottom was damaged. This cannot be repaired.

New toilets can be had for less than $100, are simple to install, and work so much better than one that is only a few years old. The technology of clearing the bowl with very little water has improved greatly.

Especially if your current toilet is from the early years of low water usage, you are going to love your new toilet. That is if you can love a toilet. I bought one Glacier Bay for under $100 that was a consumer magazine "best buy" and a Kohler for twice the price. They both work great. Was the dual flush unit worth the extra money? It's mostly a matter of what is important to you. They both do the job very well when compared with the 20 year-old models that they replaced.

It looks like the porcelain has been chipped off in the bottom. Pumie makes a pumice stone for rust marks in toilets. It may work on the streaks.

Not sure what it is but maybe this would work????

https://www.hunker.com/13417241/how-to-increase-the-water-level-in-a-toilet-bowl

You will need to get very close to see if the porcelain is chipped - material removed - or if it is a patch of stained mineral deposit - material added.

I have a cleaning business and have seen 100s of toilets. This looks similar to an issue we had with one of our own toilets when we moved into our house.

There may be a better way, but this is what I did:

With a toilet brush I plunged as much water as possible back down the hole. Then, using a small Dixie cup I bailed out the rest of the water. A small amount of water remained, but I got as much as possible. I discovered that the dark patch was on top of the porcelain and not missing porcelain. You simply can not see well enough through a full bowl of water. What wound up working best was chiseling away at it with a plastic spoon. Plastic so it wont damage the surface and can be thrown away. Many plastic utensils won't be strong enough, but find that supply of random plastic cutlery in the back of a drawer and you should be able to come up with a heavy duty clear one or a Wendy's spoon. After a few attempts it was the Wendy's spoon that ultimately prevailed. Strong enough with a sharpish edge. It took awhile. Layers upon layers of hard water deposit. We have very hard water. Had I realized beforehand that it was mineral deposits I would have put 2 Efferdent tablets in the bottom of the bowl overnight to try to loosen the spot a bit.

Vinegar and baking soda was a good suggestion from Janet, that may loosen it up just as well. Ken has the best idea... new toilet. So worth it.

Alternate soaking CLR in the bowl, then bleach. One. Then the other. Do this every day and soon that stain will break up.