Are the Core Web Vitals metrics configurable at build time?

The Core Web Vitals prescribe a specific set of metrics thresholds and percentiles we believe correspond well to user expectations across a range of devices.

We encourage using our official thresholds as much as possible. If however, you would like to set custom targets for thresholds (e.g a Largest Contentful Paint performance budget of < 3s), this is possible using Lighthouse CI and LightWallet. Metric targets can be set using assertions and a performance budgets file.

An example of such assertions can be found below:

{
  "ci": {
    "assert": {
      "assertions": {
        "largest-contentful-paint": ["warn", {"maxNumericValue": 3000}],
        "viewport": "error",
        "resource-summary:document:size": ["error", {"maxNumericValue": 14000}],
        "resource-summary:font:count": ["warn", {"maxNumericValue": 1}],
        "resource-summary:third-party:count": ["warn", {"maxNumericValue": 5}]
      }
    }
  }
}