Overcommiting CPU Resources in Kubernetes
You should be able to use the flag spec.containers[].resources.limits.cpu to set your desired state on a deployment.

The official docs here and here have some examples of how to specify this in the yaml.  You can set a global default along with min/max limits:

spec:
  limits:
  - default:
      cpu: 1000m
    defaultRequest:
      cpu: 300m
  - min:
      cpu: 300m
  - max:
      cpu: 1000m