You don’t absolutely need formal coaching to succeed but coaching can be very helpful. Here’s why:
Coaching classes often provide structured study plans that cover every topic you’ll see in the exam: Physics, Maths English, etc.
You get regular practice mock tests and feedback which helps reduce exam anxiety.
Coaching can help you stay consistent with your studies which is very important when preparing for a serious test like the cpl entrance exam.
If you decide not to join coaching you can still do great:
Use NCERT books and other good reference books for Physics, Maths and English.
Make a schedule: break up your subjects revise often practise reasoning and past exam questions.
Try mock tests: they help you get familiar with exam format and timing.
Join study groups or online forums to clarify doubts.
Coaching is a boon especially if you want guidance discipline or lack clarity in some topics. But if you are a motivated learner disciplined and have good resources you can prepare well on your own.