How can I add unfurl_links in Slack message

Question

In the Slack message format example block below, how can I add unfurl_link option?

{
  "type": "section",
  "text": {
    "type": "mrkdwn",
    "text": "New Paid Time Off request from <example.com|Fred Enriquez>\n\n<https://example.com|View request>"
  }
}