You might put off having to replace the washer by adjustment, but overflowing is usually caused by a worn out washer.
Adjustment method depends on the type of fill valve. If a commonplace Part 2 brass valve with a ball on a brass float arm, then you can lower the ball or bend the arm - don't snap it though. If a Part 1 valve then have no choice but to attempt bending.
However, I would never bother bending - it's a ten minute job to replace the valve. Turn off the mains first, or if the mains flow is poor then just leave the kitchen cold tap open for a bit.
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