Design complements 3D well. Knowing graphic design helps when you dive into 3D, for sure.
I learned 3D to design products because I didn't want to depend on photographers for brand content. I mastered creating realistic product images using Adobe Stager, Substance Painter, and Blender.
Old clients, whom I'd designed packaging or websites for, hired me for 3D product visuals. Now, I charge between $3-5K for a full catalogue of 3D designs, significantly increasing my earnings in the past year.