Am I using the correct components for building a PID-controlled line-following robot with two wheels? The components I plan to use are:
If the project works properly, I am planning to convert it into a PCB.
Your list is missing wheels. The best experience for your first project (aftre blink withtout delay and serial basics) is to buy a kit which includes all the parts, drawings, assembly videos, tested code examples, and support. You will have further support here for the code and devices.
As somebody has already pointed out, your list is missing wheels. You have to select a wheel compatible with the motors. * Running 6V motors on an 11.1V battery directly can burn them out.
Use PWM + TB6612FNG to control voltage output, or add a buck converter to step down the voltage.