How to import custom fields created using third party plugins?

If you are using any third-party plugin to create custom data fields, then it will be stored as metadata. When importing custom fields, the import file must have the data in the same format as required by those plugins. The easiest way to identify the format is by exporting the sample existing data/product on the site using the plugin. Make sure you have enabled the option of Hidden metadata on the export mapping screen. Use the exported file as a template to import the data back.