So i have a white corolla and well i live in a house which has pine tree aka sap keeps falling on my car. So its been filthy and i decided to go wash and there was brown Stains on my car so i went to get Turtle Wax Renew Rx Rubbing Compound and Heavy Duty Cleaner and well now the paint looks duller in those spots. There was some white on my applicator, so im sure i ruined the clear coat, i dont want to go to some professional so how could i fix this? I dont want it be spread and ruin the paint more.
the only way to fix it is to paint it.
but if you leave it then it's not going to "spread". Just put some wax on it.
Do i add a layer of paint then clean coat it?
only if you can see primer. if you really need to fix it then let a professional do it. It won't cost that much.
That's the downside of clear coat finishes. They look great when new but when clearcoat fails it looks really bad and the only fix is to stip and repaint the affected panel(s). Old-school single-stage finishes could be buffed and shined when they got dull as long as they didn't get down to the primer.

See a lot of this here in Texas.
but is the single stage finish as durable as a clear coat?
That likely depends on the formulation and quality of the paint.
You could try some Turtle Wax White Polishing Compound to see if you can bring back some of the shine. Next car, use a car cover, or build a carport/garage.