Most people print these on larger cardstock sizes, anywhere up to 12" × 18", depending on how they plan to frame or display them.
Two of the most common choices:
For paper, it mostly comes down to the vibe you want:
100# uncoated cover
Soft, matte, gallery-style feel - great for illustrations.
100# silk-coated cover
A little shiny, slightly richer color pop. A nice choice when you want something a little flashier ✨ - great for photography.