7hours layover Beijing from Thailand back home to Canada

Good day,

We are traveling back home to Canada from Thailand with a 7hours layover to Beijing. We would like to make a quick cab ride to the closest Great Wall part, an 1hour north of the airport.

How does it work for the 24hours “visa”?
Do we just go through regular immigration?
Do we have to apply and fill out some “forms”?

Please advise

Kind regards,

Alex