Absolutely, a guest can also create a return request with Magento 2 RMA Extension.

Read this guide on How to Configure Return Merchandise Authorization (RMA) in Magento 2 Store to setup this extension.

Here are the few more resource to help you get most out of this Magento 2 RMA Extension.

• How to Manage Customer Orders Returns in Magento 2
• How to Setup Order Confirmation Email in Magento 2
• Streamline Product Returns with RMA Magento 2 Extension
• How to Manage Return Requests Effortlessly with Magento 2 RMA Extension