Laravel chaining reations?

Description

I have several Models:
Course (id, line_id, category_id name...)
Category (id,name...)
Line (id, name...)
Semester (id, year_id, name...)
Year (id, study_id, name...)
Study (id,name...)
and 1 pivot table
course_semester.

I am already able to make an object/array of a course which contains:
course = {
  id,
  name,
  ...,
  line = {
    id, 
    name, 
    ...
  },
  category = {
    id, 
    name, 
    ...
  },
  semesters = {
    {id, name, ...},
    {id, name, ...},
    ...
  }
}

What I want to add in this object/array is:
study = {id, name, ...}
    
    
How would I do this?