Magento 2 contact form with support for custom fields.
Based on (https://github.com/SlavaYurthev/Contact-M2/)
composer require imi/contact-m2
The plugin is configured at Stores -> Configuration -> Custom Contact -> Contact Us
Email type fields will receive the email. If you want to ask for another email, use the text type.
You can use the following snipped to include all the non-empty fields:
{{var _all_fields_html|raw}}