By using this code snippet, you can create the configurable product. Make changes accordingly yours

<?php
    $productId= 03; // Configurable Product Id
    $objectManager= \Magento\Framework\App\ObjectManager::getInstance();
    $product= $objectManager->create('Magento\Catalog\Model\Product')->load($productId); // Load Configurable Product
    $attributeModel= $objectManager->create('Magento\ConfigurableProduct\Model\Product\Type\Configurable\Attribute');
    $position= 0;
    $attributes= array(134, 135); // Super Attribute Ids Used To Create Configurable Product    
    $associatedProductIds= array(1,2); //Product Ids Of Associated Products
    foreach($attributesas$attributeId) {
        $data = array('attribute_id'=> $attributeId, 'product_id'=> $productId, 'position'=> $position);
        $position++;
        $attributeModel->setData($data)->save();
    }
    $product->setTypeId("configurable"); // Setting Product Type As Configurable
    $product->setAffectConfigurableProductAttributes(4);
    $objectManager->create('Magento\ConfigurableProduct\Model\Product\Type\Configurable')->setUsedProductAttributeIds($attributes, $product);
    $product->setNewVariationsAttributeSetId(4); // Setting Attribute Set Id
    $product->setAssociatedProductIds($associatedProductIds);  // Setting Associated Products
    $product->setCanSaveConfigurableAttributes(true);
    $product->save();
?>