clipPathUnits

html,
body,
svg {
  height: 100%;
}

<svg viewBox="0 0 100 100">
  <clipPath id="myClip1" clipPathUnits="userSpaceOnUse">
    <circle cx="50" cy="50" r="35" />
  </clipPath>

  <clipPath id="myClip2" clipPathUnits="objectBoundingBox">
    <circle cx=".5" cy=".5" r=".35" />
  </clipPath>

  <!-- Some reference rect to materialized to clip path -->
  <rect id="r1" x="0" y="0" width="45" height="45" />
  <rect id="r2" x="0" y="55" width="45" height="45" />
  <rect id="r3" x="55" y="55" width="45" height="45" />
  <rect id="r4" x="55" y="0" width="45" height="45" />

  <!-- The first 3 rect are clipped with userSpaceOnUse units -->
  <use clip-path="url(#myClip1)" href="#r1" fill="red" />
  <use clip-path="url(#myClip1)" href="#r2" fill="red" />
  <use clip-path="url(#myClip1)" href="#r3" fill="red" />

  <!-- The last rect is clipped with objectBoundingBox units -->
  <use clip-path="url(#myClip2)" href="#r4" fill="red" />
</svg>