is possible to read values of the v-slot of a components in JS?

Below an example:

<cron-core v-model="value" :periods="periods" :format="format" v-slot="{fields, period, error}">
  {{period}}
    <div v-for="field in fields" :key="field.id">
      {{field.id}}....
    </div>
  <div>error: {{error}}</div>
</cron-core>

i’m triyng to read the ‘fields’ value without success, i cannot edit directly the sub-component, because is a predefined-component.