Any way of downgrading macOS?

I was wondering if there was any way of downgrading to macOS Catalina. Im on macOS Monterey and I'm getting a newer MacBook soon and I was wondering if I could downgrade this once I get a new MacBook. I always loved the look of the older macOS and since I'm getting a new one, I would like to have this almost as a souvenir of sorts. Sorry if this was a stupid question thanks if you have a response. Specs: 11' 2015 MacBook Air 4GB Ram 1.6 GHz Intel 128GB Storage.