Basic steps to programmatically add product attribute in Magento 2
1: Create the Setup File InstallData.php
File Path: app/code/Company/Mymodule/Setup/InstallData.php
2: Describe the install() Method
<?php
public function install(ModuleDataSetupInterface $setup, ModuleContextInterface $context)
{
}
3: Develop Product Attribute
4: Upgrade
Get more details about these steps by clicking on the link below:
How to Add Product Attribute Programmatically in Magento 2