So for example, I can change Mission Control instead of being Control and up arrow, I can change it to the right Shift key. When I press the right shift key, it goes to Mission Control. In fact, it even works as the Shift key because I can hold it down and then release it and it goes back. If you ever want to go back to standard, there is always the one at the top here. You can do the same with application windows. You can choose one of these. So I can make the right option with this too. The desk also allows this. So the dashboard doesn't, but the dashboard gets lost in Catalina anyway.
Note that another option here is the fn key. It's a little too useful for many different things, so I'll never assign it as a shortcut. But it is there as an alternative if you want it. In this way, you can actually make the unused modification keys useful. But what about the Caps Lock key. Well, if you enter the keyboard again, but instead of shortcuts, go to the keyboard screen and there is a modifier key button. Click on it and it allows you to change the modifier keys. So if you really wanted the control to be command and command to be in control, you can do it. I do not recommend doing it! It's very confusing.
But Caps Lock is also included here. So you can change Caps Lock to actually be one of these. So I can make Caps Lock an extra control key or option key or command key. I'm not sure why you want to do it. The two most interesting settings are Escape. So you can actually use the Caps Lock key as an Escape key. This is very useful on MacBooks that have TouchBar because the Escape key is part of the TouchBar. But if you prefer a physical key for Escape, you can assign it to the Caps Lock key.
You can also go to No Action. Many use this to prevent them from accidentally hitting the Caps Lock key. How many of us have tried to enter a password unsuccessfully just to realize that you happened to have the Caps Lock key down. This would stop it.
If you now want to hack your Mac to use the keys for something completely different, there is a way to do that by installing a third-party app. It's called Carabiner. It has been around for a while and it's pretty nerdy. But if you're interested in that kind of thing, you can install this, play with the settings, read some tutorials on how to use it, and get the Caps Lock key to be, say, something else.