Log out of the switch?

I'm selling my Switch tomorrow and wanted to ask if I have to look out for anything when it comes to my Nintendo Account.

Of course I delete the user from the Switch, but will my Nintendo Account also log out? If not, how do I log out of the Switch using my Nintendo Account?

And do I have to pay attention to nothing else when it comes to my data? Unfortunately I'm very uninformed.

If you go to Formatting Options in System Settings under the Console menu, you can reset the Switch to factory settings. The console is set to the delivery state and all data (your account) is deleted from the console.