Goes on: Scale
No keyframes needed: the layer springs up from zero at its in point with our house spring.

// Spring Pop-In — Coherent Motion Expressions · getcoherent.app/resources
// Springs from 0 to the layer's scale at its in point. Slide the layer to retime it.
var duration = 0.45, bounce = 0.4, delay = 0;
function sp(t) {
  if (t <= 0) return 0;
  var w = 2 * Math.PI / duration, z = 1 - bounce;
  if (z > 0.999) return 1 - (1 + w * t) * Math.exp(-w * t);
  var wd = w * Math.sqrt(1 - z * z);
  return 1 - Math.exp(-z * w * t) * (Math.cos(wd * t) + z * w / wd * Math.sin(wd * t));
}
mul(value, sp(time - inPoint - delay))
