Be careful of people spreading misinformation.
Currently the extensions are provided in accordance with the policy to relieve pressure associated with COVID-19. An extension is granted for 6 months for applicants from designated countries and 1 year from non-designated countries. Also, whether you are exempt from travel or not, and will be able to land soon, is also a factor.
The designated country list is the same that was used for medicals for TRV applicants. See
https://www.canada.ca/.../requi.../country-requirements.html
Further for an extension, the immigration medical exam should have been assessed as M1 or M3.
M1: No public health risk or danger, no public safety danger and no excessive demand
M3: A health condition(s) is present but is not expected to place an excessive demand on health or social services.
So anyone claiming that "if IRCC grants an extension then it will be for no more than 6 months" is absolutely incorrect and false.
See
#13,193