I only use a couple of things that TinkerTool enables, but it is a wide ranging tool! It’s important to note that it is only changing the built in behaviors of MacOS – it does not add functionality that isn’t already there. Having said that, there is a lot of MacOS functionality built in that is not exposed! Want to show and hide your Dock without delay? Run with a single app focused? Change the default file type or naming when taking a screenshot? Work how some Unix systems do and automatically activate windows as you mouse over them? All available, along with hundreds of other settings.
Explore, enjoy, and remember what you changed so you can change it back if you want to!