$_product->getResource()->getAttribute($attributeCode)->getFrontend()->getValue($_product);

$attribute_value = $_product->getData($attributeCode);

$eavConfig = $this->objectManager->get('MagentoEavModelConfig');
$attribute = $eavConfig->getAttribute('catalog_product', 'color');
$alloptions = $attribute->getSource()->getAllOptions();
foreach($alloptions as $option) {
    $label = $option['label'];
    $AllOptionsArr[$label][] = $option['value'];
}

$products = $this->_productRepository->get($sku);
if(is_object($products->getCustomAttribute($attributeCode))){
    return $products->getCustomAttribute($attributeCode)->getValue();
}

<?php

$objectManager = MagentoFrameworkAppObjectManager::getInstance();
$atrributesRepository  = $objectManager->create('MagentoCatalogModelProductAttributeRepository');
$selectOptions = $atrributesRepository->get('AttributeCode')->getOptions();
foreach ($selectOptions as $selectOption) {
    print_r($selectOption->getData());
}