Ok, you’re starting with an Application.
Given an instance of Application named application, then the set of Applicant would be application.applicant_set.all() in the view (or application.applicant_set.all in a template).
Now, if applicants = application.applicant_set.all(), then for each applicant within applicants, applicant.person is the instance of the Person object, and applicant.person.address_set.all() is the collection of all their addresses. Likewise, applicant.person.employment_set.all() is the set of all Employment objects associated with that person.
So what you’re likely to end up with are a set of nested loops, where you will iterate through these various details for each on the individual involved.
(Side note: Once you have your desired code working, you will want to add the appropriate prefetch_related clause to your query to prevent an N + 1 or even a 2N + 1 situation.)