There are 2 options when it comes to sending review email - you can use the Roadmap server to deliver these, or you can integrate Klaviyo to send these emails for you.
In both cases, you are able up the review emails.
Roadmap has a code block where you can drop in the code for your custom email, or, if you want to use Klaviyo, then you can add your Klaviyo API key into the Roadmap settings, and this will allow you to use Klaviyo instead where you can config your own flows and email designs.