It is not mandatory to take up training/ coaching for IELTS preparation, if an applicant is clear with the course structure, the exam pattern and the score band requirements then self-study and assessment will suffice to crack the IELTS exam.
But it is also factual that IELTS training with proper guidance and systematic approach would shape up your skills and abilities to become more proficient in the English language which will clear your way to start your journey to your desired Country.