Drupal 8 - Get a list of content types

// 1st way
$content_types = \Drupal::entityTypeManager()->getStorage('node_type')->loadMultiple();
// If you need them to disply in a drop down.
$content_type_options=[];
foreach ($content_types as $node_type) {
    $content_type_options[$node_type->id()] = $node_type->label();
}
 
// 2nd way
$content_types = \Drupal\node\Entity\NodeType::loadMultiple();
// If you need them to disply in a drop down.
foreach ($content_types as $node_type) {
    $content_type_options[$node_type->id()] = $node_type->label();
}