Layover in Paris - sight seeing
 

I have a 10 hour layover in Paris getting into CDG around 7am, so I have the whole day. Could i just go out and sight see for 5-6 hours and come back? I know we are in COVID times and I'm fully Vaccinated.

You would need to fully meet France's entry requirements (passport/residence, visa, COVID-19 test, forms, QR code, etc.) at the time of your trip.

You might want to think about whether you would want to attempt to store your carry on stuff at CDG instead of taking it with you for the day.

I've done it, and it actually was easier/smoother than I expected. This was back in 2010, so some things may be different, but in general I would say it's doable.

What I don't recall is what we did with our carry-on suitcases. I believe there was a left luggage office at either the airport or at a main train station that we had to pass through.

Assuming that you take the RER from CDG to Paris, there's no reason to get off at a train station such as Gare du Nord. Pick a station that's close to what you want to see and do, or transfer directly to a subway line to where you want to be.

BTW, watch out for pickpockets, especially on the RER line from/to the airport, where foreign tourists are targeted.

Allow lots of time before your departing flight to go through exit passport control and security at CDG. It's not unusual with a nonEU (etc.) passport to wait more than an hour in the special business class line (even longer for coach passengers without airline status).