No, applying for PR status does not give you the right to keep working with an expired work permit. Your employer needs to get an LMO and you need to apply to extend your work permit to continue working. If you applied for PR through PNP, you will not need an LMO to extend your work permit once you get your PNP nomination. If you can not extend your work permit, you have a 90 day grace period after it expires during which you can apply to restore your status and for example change to visitor.