if the game uses steam DRM, steam emulators cant do anything with that. you additionally need a separate tool that strips the steam DRM
see here: https://gitlab.com/Mr_Goldberg/goldberg_emulator/blob/master/README.md
(Assuming the games have no DRM and use Steam for online).
but indeed, it seems not all games need it:
If you are a game developper and made the mistake of depending too much on the steam api and want to release of version of your game without it and don't want to rewrite your game, this is for you.