Change Nintendo Switch keyboards?

A friend of mine has super cute symbols and characters on his Nintendo Switch. I would also like this and he said that there's a keyboard that says "symbols" or something where all the things are.
However, I can't find where to add keyboards etc. If someone could help me that would be very nice ^^

I have already searched btw on the Internet myself, but only found how to connect your mouse and keyboard to the switch… ^^ '

Wherever you change the language on the keyboard, there will come "signs" and there are symbols

Ah oki, thank you ^^