How can I simplify CTRL SHIFT COMMAND 3 in Chrome?

Roger, thank you very much! Your answer is very clear and helpful. But only for the first step of what I need to do.

I need to make a screenshot of a screen in a fullscreen mode and save it to the clipboard, not desktop.

First I need to enter fullscreen mode. Here your answer is helpful. You've wrote how to do it quickly.

Then I need to make a screenshot.

In my mac it's SHIFT+COMMAND+3 (it's not my setting, it's defoult)

To save the shot to the clipboard I need to press CTRL aditionally (at the same time).

So I want to simplify this action.

I don't know the name of command "to make a screenshot" to use your instruction above, but it seems to be possible the way you wrote.

You are a genius!!! :) :) :)

That's it!

Thank you so much!