formStimulusIntlTel.php

<?php

namespace App\Form;

class MyGreatForm extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options): void
    {
        $builder
            ->add('tmpPhone', TextType::class, [
                'required' => true,
                'attr' => [
                    'data-intl-tel-input-target' => 'input',
                    'autocomplete' => 'tel'
                ]
            ]);
    }
}