The problem is that when you're starting out on graphics, you don't even know what you're capable of doing with the hardware that you have, and the distance between manipulating things on the hardware and putting something on the screen can seem dauntingly far away.
My advice, start out with OpenGL 1 (the old glBegin()/glEnd() stuff) or Raylib (raylib.com) where you begin to get accustomed to really basic stuff (primitives, transformations, etc.). Then do the LearnOpenGL tutorials to learn modern graphics concepts (vertex buffers, shaders, render passes, etc.) Once you've done this you might have enough knowledge to make a simple game/visualization/application, and you'll know yourself if you need to study D3D12/Vulkan or not.
My advice, start out with OpenGL 1 (the old glBegin()/glEnd() stuff) or Raylib (raylib.com) where you begin to get accustomed to really basic stuff (primitives, transformations, etc.). Then do the LearnOpenGL tutorials to learn modern graphics concepts (vertex buffers, shaders, render passes, etc.) Once you've done this you might have enough knowledge to make a simple game/visualization/application, and you'll know yourself if you need to study D3D12/Vulkan or not.