This is a commonly-asked question.
You’ll need to send HTML, not plain text as output by the Text Aggregator.
To do that you need to use a Text Replace module to add paragraph tags to the start and end of each line before you can use it in the email.
Original string:
Output, HTML:
For more information on how to do this, see https://community.make.com/t/how-to-start-a-new-paragraph-adding-signature-in-email/16781/2 and https://community.make.com/t/claude-gpt-new-line-outputs-for-html-email/16805/2