I found it much easier to assign a class to the input field (in my case they are created dynamically).

<input
  class="d-inline texts"
  matInput
  formControlName="text"
>

Then I just applied the following pure javascript to autofocus on the last input field created:

    setTimeout(() => {
      const elementsByClassName: any = document.getElementsByClassName('texts');
      elementsByClassName.item(elementsByClassName.length - 1).focus();
    }, 0);