If you are using a third-party launcher, it probably has built-in functionality to automatically install mod loaders. Sodium is a Fabric mod, which means it requires the Fabric Loader. It contains important instructions on how to prevent crashes and other performance problems. Please make sure you read the Known Issues section on this page before you install Sodium.
It boasts wide compatibility with the Fabric mod ecosystem when compared to other rendering-focused mods, and it does so without compromising on how the game looks, giving you that authentic block game feel. Sodium is a free and open-source mod for Minecraft 1.16+ clients which greatly improves rendering performance while fixing some graphical issues.