Do I have to pay a protection fee to apply for a patent for invention?

The invention is like this. It depends on whether your design idea can solve the existing technical problems, whether it is practical, whether it is novel and whether it is creative. If these are all in line, there is no problem in applying for a patent, and there is no need to make specific samples. If your samples are made public, it will affect the novelty. When you apply, you pay the application fee. If your patent is really valuable, I suggest you find an agent to write it. It costs more, but it should be worth it. I suggest you find a better agent. If the application is approved, the annual maintenance fee will be paid every year instead of the protection fee.