If you are unable to get the meds done within 30 days, you should immediately send a webform informing IRCC that the panel physicians are not available and / or closed due to COVID-19 and therefore you need additional time. As per the most recent COVID delivery instructions, IRCC will provide you with additional 90 days.
If you are still unable to provide the meds within the additional 90 days, then you should again send a webform before the expiry of the time frame to seek another extension.
Also the delivery instructions clearly state, "Note: If your application is in progress it will not be closed or refused because of your inability to complete your IME in time due to COVID-19. We’ll automatically give you 90 days to complete this step."
However, since your case is for remeds, which is not directly referred to here, you should send a webform.
See
https://www.canada.ca/en/immigratio...application/medical-police/medical-exams.html