After upgrading to CD2021 when I press Shift and double click on Rectangle it doesn't draw a Rectangle around page or selected objects
I know it's not much help, but both functions work fine here. Try resetting your workspace to default, I've had some issues before with workspaces interfering with things you wouldn't think are relevant.
both options works fine on CorelDRAW 2021, it was tested by several users on the facebook groups. It was disabled only on a few users who have a pirate copy
So how can pirate copy users enable it?
And place is your original copy fast in carrying out commands?