Is there a way to automatically send a summary of a completed form to the person who submitted it?

After a person has completed a form and submitted it, is it possible to generate an automatic response that is not only a thank you page but also a summary of their submissions?

This can be easily done in two ways:

1- You can configure autoresponder email that will automatically send an email to your users immediately after submissions, and you can edit the emails to include specific details and other text etc. 

to achieve this please follow this guide:

Setting Up an Autoresponder Email

2- You can add the submission details to your Thank you page using the Form Fields feature in the editor, to do so:

1. From your edit form page, Click on Settings.

2. Select Thank you page.

3. From "Show a Thank you page" editor, Select Form Fields.

From "Form Fields" selects the fields you want to show your thank you page.