netbox/netbox/templates/dcim/device_component_edit.html

{% extends 'generic/object_edit.html' %}
{% load form_helpers %}

{% block form %}
  <div class="field-group mb-5">
    {% if form.instance.device %}
      <div class="row mb-3">
        <label class="col-sm-3 col-form-label text-lg-end">Device</label>
        <div class="col">
          <input class="form-control" value="{{ form.instance.device }}" disabled />
        </div>
      </div>
    {% endif %}
    {% render_form form %}
  </div>
{% endblock form %}