is it okay 4 years old used UPS Battery filling sulfuric Acid insted of Distilled water?
A UPS uses sealed lead acid batteries (SLA), those are not intended to be refilled.
They are filled with a elektrolyte gel instead of liquid.
Refilling could theoretically work, if you're able to remove the gel. Which means removing the top, which is ultrasonically welded.
The rubber caps you see there are intended as pressure relief valve.
When adding water you lose the ability to operate them in all orientations.
Replacing the battery with a car battery may work, but do not expect improved runtime, that is not what car batteries are designed for. Car batteries excel at high current, not high capacity.
tl;dr Just buy a new battery. It's $20. ($5/y)