Note: The regular expression has a starts with (^) and ends with ($) metacharacter and will not match any of the sentences. Without the starts with (^) metacharacter the first and second sentences would match and the supporting element (Employee ID) would be within 100 character proximity.
Reference:
https://docs.microsoft.com/en-us/microsoft-365/compliance/create-a-custom-sensitive-information-type?view=o365-worldwide