A closed (employer-specific) work permit can't simply be 'bridged' or amended in place to cover a new role — despite what you may have read:
- The employer generally must go through the full LMIA process again with ESDC to hire you into the new role or under new conditions, unless the job qualifies for an LMIA-exempt category (a narrow subset of occupations/programs).
- Once the new LMIA is approved, you apply for a new work permit reflecting the updated employer/role/conditions — the old permit isn't simply edited.
- While waiting, you can request interim work authorization. Submit a webform to IRCC asking for permission to begin working in the new role while the new work permit application is in process; this isn't guaranteed but is a recognized route some applicants use.
Don't rely on informal advice that a company can just 'change the conditions' on an existing permit — treat it as a new LMIA + new work permit application unless your occupation is confirmed LMIA-exempt.