ipsos-components/src/material-examples/input-hint/input-hint-example.html

Material Design components for Angular

<form class="example-form">

  <mat-form-field class="example-full-width">
    <input matInput #message maxlength="256" placeholder="Message">
    <mat-hint align="start"><strong>Don't disclose personal info</strong> </mat-hint>
    <mat-hint align="end">{{message.value.length}} / 256</mat-hint>
  </mat-form-field>
  
</form>