Only root user can open Visual Code Studio, but Visual Code Studio tells me not to use it as root

If I try to start VSC as root, I get a warning. If I sudo into another account and try to run VSC, nothing happens. I do...

code my_file.txt

...and there is no error, but VSC does not open. The operating system is Redhat 7.

If I use the verbose flag, I see...

$ code my_file.txt --verbose
No protocol specified

(code:5734): Gtk-WARNING **: 06:51:30.910: cannot open display: :0