Quarantine Plan is not a requirement to apply for TRV. It is a good idea to discuss a brief plan in the cover letter, however. This will show the deciding agent that the visitor is aware of a 14 day quarantine requirements and the rules that need to be followed during the 14 days.
My wife landed @ YYZ via YVR last Thursday. She got a call on yesterday from a health official to find out if she is in quarantine. They asked her a bunch of quarantine related questions. She asked the agent if I am allowed to leave home or go to work. The agent said: "Yes, your husband CAN leave home and CAN go to work. Only foreign visitors to Canada are subject to the interim order.