You most certainly can.
https://www.cic.gc.ca/english/helpcentre/answer.asp?qnum=1184&top=16
I read the experience of someone in a similar situation as you on another thread. What he did upon receiving COPR (whilst in Canada) was travel to the the US and back via Niagara to Land. He applied under FSW-O stream. I don’t know what the Landing requirement is for FSW inland and CEC so I can’t say if traveling out and back to Canada is required to Land.
Thanks for this! I was more so thinking if I don't have my COPR before I come back in... if I'm still waiting for the golden email. I wouldn't have a valid work permit or COPR, so I guess I would just be coming in as a tourist? But wouldn't they want to see a leaving date at the border? (flying in to Seattle anyways)