‘sudo su’ is not a valid username. It cannot be used directly at the text mode login prompt.
When you install Fedora, you should have an new user created with the “sudo” access.
Login with that user first, then when running command needing the “root” access, just prefix that command with "sudo ".
And root user is locked by default, unless you set a root password during the installation.
You can enable the root account by setting a root passwd afterwards by
sudo passwd root
(then follow the prompt to enter the new password for root, twice.)