Currently, it is not possible to set a value containing line breaks in the "Default Response" of the type "Paragraph" field.
example: line1¥nline2<br>line3\nline4\n\rline5

So, when editing the form, could you please make it possible to set a line break in the "default response" of the type "paragraph" field?

Workaround

From the custom field default value settings, set the default value including line breaks.

• https://support.atlassian.com/jira-service-management-cloud/docs/add-a-new-custom-field-to-a-project/