UBTween.Scale interpolates the scale of an object.

Supported Objects:

Target	Value changed
Transform	Transform.localScale
RectTransform	RectTransform.localScale

Use Current Scale As Start :

UBTween.Scale(
    transform,      // Target Object
    Vector3.zero,   // End Scale
    1f);            // Duration

Using float will set all the axis to that number :

UBTween.Scale(
    transform,  // Target Object
    0f,         // End Scale
    1f);        // Duration

Specify Start Scale :

UBTween.Scale(
    transform,          // Target Object
    Vector3.zero,       // Start Scale
    Vector3.one * 2,    // End Scale
    1f);                // Duration

Using float will set all the axis to that number :

UBTween.Scale(
    transform,  // Target Object
    0f,         // Start Scale
    2f,         // End Scale
    1f);        // Duration

Gif Code :

UBTween.Sequence sequence = new UBTween.Sequence()
{
    UBTween.Scale(transform, scale, 1)
        .SetEase(EaseType.OutExpo),

    UBTween.Scale(transform, scale, Vector3.one, 1)
        .SetEase(EaseType.OutElastic)
        .SetDelay(1f)
}.SetLoop().Start();