Hi, graphic design span many disciplines and each one will have different requirements. Unless she does some short of 3D or video rendering intensive workloads GPU doesn’t matter that much. Im am UX designer (formerly graphic designer) and a powerful CPU, something like an AMD Ryzen 5800x or similar, plenty of RAM (at least 32Gb) and SSD HD (nothing fancy, anything will do) should be enough. Sadly, design software hasn’t evolved enough to take advantage of better performance.

However I’m not a Linux user (although have been considering it) so my main concern would be how the software she uses is Linux compatible or can be properly emulated without performance or stability issues. If she is working professionally FOS software won’t do it, you need default industry software.

I mainly use Figma and to lessen extent Adobe Photoshop and Illustrator. Figma can run entirely in a browser but I’ve seen reports of slowdown (to the point of being unusable in some distros). Adobe apps seem to be very hard to emulate to the point of seeing people recommending using a Windows VM. So I rather start checking the software rather than the hardware.