I want to break the build if coverage drops below certain percentage. Currently test runs and coverage is generated if I run below command.
COVERAGE=true ember test
but I don't see a way to break the build based on coverage percentage. Request to help me on this.

It is sadly not built-in. However, some people were successful setting coverage threshold with Istambul
I attached a picture of the configuration I found at https://github.com/kategengler/ember-cli-code-coverage/issues/23
If you are looking to fail the build in a CI/CD pipeline, an easy alternative road would be to:
grepto parse the generated output that contains the coverage resultbcNote: We are using EmberJS at my company but we don't have coverage thresholds configured on emberjs projects . It's configured on React projects tho because Jest has that built-in