KnowBe4 uses common URL identifiers in many of their campaign emails. This does not always apply. Campaign content is intentionally designed to vary, to mimic actual phishing behavior.
In the screenshot below, you'll see a URL commonly used by KnowBe4 for phishing campaigns.
Emails generated by KnowBe4 also have custom headers, for easier identification by anti-spam / phishing security systems, which will, ideally, allow the test to reach the end user.