I need to create a registration form in PowerApps and email the form details on submit button click.
As @Mark mentioned you can use following link
How to create a User Registration Form using PowerApps, Flow & SharePoint Lists
And to send an email through PowerApps – just create a workflow using MS Flow, that will be triggered when an item is added into SharePoint list.
You can customize the email body as per forms fields.
The article below details how to create the registration form (using PowerApps and SharePoint). It doesn’t cover the email part though.
There’s also another solution using TypeForm, if you want to get anonymous users filling in the form and then have it stored in SharePoint.