I bought a jar of my Camaro's paint color. I coated with the primer x2. Then after applying base color with brush and letting it dry, the paint is thick with ridges. I tried 2000 grit but tis not touching it. Whats the best way to level it

You might have something on there that really isn't going to sand out well especially if you brushed it on. There's not really anything you did so far to the car that is considered a correct way to touch it up...but if you really want to try to sand it, put p600 wet sandpaper on a very hard block (small piece of wood for example) and wet sand it flat. Try not to ruin the adjacent paint.

Don't sand it.

When touching up the primary rule is to contain the repair to the damaged area only, not extend it.

Get a cloth, wet with acrylic thinners and wipe off that mess. Use the cloth wrapped around your finger and make fast light swipes, taking off just a small amount at a time. Don't spread it all over the surrounding area. If done carefully you may even leave a layer of the primer in the bottom of the scratch.

You'll need a very small pot, about the size of a thimble. Mix 8 drops of your colour coat with 8 drops of high quality, slow thinner. We use an eye dropper to measure out the thinner. Mix, then moderately load the brush with the paint load near the tip, which should be flattened out.

Apply the paintby barely touching at one end of the scratch, lifting the brush a little so that it isn't actually touching the car but the paint is being drawn, by surface tension, down into the scratch. Move along the scratch until your paint load is used, then repeat as necessary.

Allow that coat to dry, maybe 30 minutes in moderate sun, and repeat the process. You may have to put in 3 or 4 coats until you end up with a slightly raised ridge of paint. Allow to dry fully - an hour or two ,depending on conditions.

Now wrap a single layer of cloth around the end of your finger and wet with some polish. Polish down that ridge using very fast, but a very light back and forth motion. You want to end up with a slightly raised welt of paint. Don't try to polish down level - that will expose the jagged edges of the scratch. Leave it up a bit and the paint will shrink in the middle over the next few days.