Can you downgrade a new MacBook from Catalina to Mojave?

Hello everyone!

I may be in the market for a new MacBook in the future, but I don't want Catalina. (In addition to general bugginess I'm hearing of, I have some Steam games I know haven't been updated to 64bit and I don't want to lose that compatibility if I can help it.) I know you can use Time Machine to revert to a previous version, but will that work if I purchase a new laptop?

Thanks!