Which situation you can apply study permit extension within Canada?

The applicant hold valid work permit , but he/she will change change status as a student.

The applicant hold valid study permit, but his/her study permit will expire soon

The applicant hold valid study permit, but he/she will start to study in new school or new major.

The applicant’s spouse or parents hold valid study permit or work permit, she/he can apply the study permit extension