I can't speak for both games you listed, however for WoW - Blizzard games tend to have a good reputation for running on Linux (one of the few good things I like about Blizzard). Sometimes there are a few bugs here and there (OW had a mouse cursor locking problem) but generally they're pretty good.

I have been playing Diablo 3 on Linux for as long as I can remember, even before the massive rise of Linux gaming from the introduction of VKD3D/DXVK/Proton. I know D4 was working in Linux even during the betas, and I've heard StarCraft players who've said the same.

Of course, the system requirements never mention Linux as an officially supported platform, but I can't say I've ever heard of a Blizzard game that doesn't work on Linux (games they develop - games like CoD and originally Destiny 2 where they were only the publisher/launcher host is a different story) so I'd be very surprised if WoW doesn't work.

IIRC Blizzard's anti cheat ("Warden" I believe) is mostly server side which makes things way easier - I mean hell I know a lot of their games even supported Mac OS.

And as the others have linked, for MSFS you can check Proton but I hear the reception is good there too since it's rated as Silver on there.

These days I'm usually just playing the Diablo games from them, and I just use the Bottles app which makes it really easy to play non-Steam games. It even has an option to install the Battle.net client for you, then you login, install the game, and click play - it's super simple.