netbox/netbox/templates/dcim/device_component_edit.html

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

{% block form_fields %}
    {% 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 %}
{% endblock %}