How to add parent div with form builder in symfony - symfony

Question

form created by form builder
<form name="post" method="post">
<div id="post">
<div class="form-group">
<input type="text" id="post_title" name="post[title]" required="required" class="form-control"/>
</div>
<div class="form-group">
<textarea id="post_content" name="post[content]" required="required" class="form-control"></textarea>
</div>
<div>
<button type="submit" id="post_postAdd" name="post[postAdd]" class="form-control btn-primary">Create</button>
</div>
<input type="hidden" id="post__token" name="post[_token]" value="ab35508c9.6MnqGe6WDVVVtkdRga_Ahtt5kDssuXri3JBx4HcVdOw.gKCQYdugYSw2_x88wN2y6Z5P_mtJyxaqm95GhkRDP52qoYFjucJOGyTuIA" />
</div>
</form>
i want this. How i create parent (div) elements one or more like below with form builder. Not in twig.
<div class="oneMore"> <!-- I need this element -->
<div class="iWantToAddThis"> <!-- I need this element -->
<div class="form-group">
...input...
</div>
<div class="form-group">
...input...
</div>
</div>
</div>
PostType.php. I created form like below.
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder
->add('title', TextType::class, [
'attr' => [
'class' => 'form-control'
],
'row_attr' => [
'class' => 'form-group'
]
])
->add('content',TextareaType::class, [
'attr' => [
'class' => 'form-control'
],
'row_attr' => [
'class' => 'form-group'
]
])
->add('postAdd', SubmitType::class, [
'attr' => [
'class' => 'form-control btn-primary'
]
]);
}
_form.html.twig (I don't want to add anything in twig)
{{ form(form) }}