This would be a very useful enhancement! Being able to preview dynamic email content directly in the browser would definitely save time, simplify testing, and help catch layout or data issues early. 

Hi! You can already preview the email directly in Service Studio. For the parameters or expressions you're using, just set the 'Example' property to see a sample value in the preview. 

Also, both the browser and the email provider can affect how the email is rendered. 

You can use tools like WPOven to view your email in browser, just follow instruction in this link:

https://www.wpoven.com/tools/free-smtp-server-for-testing

Hope this was helpful.