So you've got a typescript file in IntelliJ and it's full of red squiggly lines. It seems that you've tried one million different options in your tsconfig.json file but nothing would work. What can you do to fix this?
For some reason sometimes IntelliJ isn't picking up on the changes properly. But what you can do is to call the "Restart TypeScript Service" Action. Simply hit "Shift Shift" and start typing the name of the action.
Afterwards, everything should look good!
If not, then it's probably actually your configuration. You can also double check for example by downloading VSCode and opening the file there and see if it reports the same issue.