In 99% of games, your save files will be stored outside the game's main folder (Steam/steamapps/common/"game title"). Means your save files are safe whenever you uninstall a game.
If you want to be sure about where your save files are located, just use Google to figure it out.

Save games are stored on your PC in 99,99% of all cases and will remain even if you uninstall a game.
The most common place is your "My Documents" folder in Windows.
Also, all games that support Steam Cloud ( and if you have it active in your client settings) will automatically upload the latest save games to the cloud and download them again if needed when you install/play the game again in the future.
Its very rare to lose your save games nowadays.

Just use Google and look for "game xyz savegame location", usually you will be greeted with proper informations regarding the specific game.

Often from here: https://www.pcgamingwiki.com/wiki/Home

There also is a tool for dozens of supported games to find and backup the savegame data.

https://www.gamesave-manager.com/

Different games save to different locations but nowadays the saves are stored outside of the games own folder, so that uninstalling the game keeps them from being deleted.

Everything is a nice tool that can be utilized for such circumstances and makes it easier to find stuff.

https://www.voidtools.com/