how can i shrink a sphere when i shoot it

[dry arrow]

i want my core(sphere with particles) to shrink when i shoot it but idk how

[dusky turret]

partiles should have a size over lifetime module
for regular objects such as a sphere, you could reduce the transform.localScale in update or something

float scaleValue = transform.localScale.x;
scaleValue = Mathf.Mas(scaleValue - shrinkSpeed * Time.deltaTime, minimumScale);
transform.localScale = new Vector3(scaleValue, scaleValue, scaleValue);

you can define the variables minimumScale, shrinkSpeed etc like you want

and do the shrinking somewhere in Update for example