When this school year ends, your 2020 – 2021 courses in Canvas will become “past enrollments”. You will still have access to them to see what they contain and can import any information from them into a “new course” when the 2020 – 2021 courses are made available.
Here are directions on how to do this: https://community.canvaslms.com/docs/DOC-12935-415257077
If over the summer you are building new Canvas lessons, create them in your Canvas Sandbox and import them over to your 2021 – 2022 courses when they are made available using the directions above.