I expect you have a remote instance(local ones won't have a big problem since you could just code-server &, sending it into the background and using X forwarding for the display. 😉 trick)
The remote instance doesn't have a GUI. IF you have a local machine with Xorg(the most preferred windowing system in the Linux world), you are in luck. But on a server, it's hard. You'd end up getting a lot of useless software and finally choosing noVNC. Here's my suggestion. Install Xorg onto your machine. Get Xfce or LXDE. After that, install noVNC(people say it's sudo apt update && sudo apt install novnc) and visit port 6080(hope you know how to deal with that).
Maybe you could get to see Tkinter work on code-server. If it's a Docker deployment(expected), add the respective lines to the Dockerfile, make sure it doesn't break(happened a LOT of times).
After that, you can upgrade code-server and enjoy the GUI.