I don't play civ6, but I've managed to play quite a few Windows games on Linux with Proton, Lutris and before that with Wine. The two most important factors fo

I don't play civ6, but I've managed to play quite a few Windows games on Linux with Proton, Lutris and before that with Wine. The two most important factors for a game to run well are 1) the version of Wine/Proton you're using and 2) the version of your GPU driver you're using. Rolling release distros like Arch are great for gaming, since you always have the last version of Wine and of your GPU driver. It's a real pain in comparison on fixed release distros like Ubuntu, especially if like me you stick with LTS releases. By using Proton within Steam Play you at least don't have to worry much about the version of Proton; just make sure you've not forced an old release and Steam will chose the right one for you. Same when using Wine within Lutris. Your only remaining duty is to make sure you're running up-to-date GPU drivers.