There is no app that will magically teach you to be a better coach. Becoming a better coach is a process. It requires daily investment in time and effort to achieve mastery of the skills necessary. Coaching is a people profession – it is not high tech; it is high touch. Technology and science should inform what we do, not drive what we do as coaches.
Know your strengths. Know your weaknesses. Enhance your strengths and improve your weaknesses. Know you sport, leave no stone unturned to learn all you can about your sport. Learn from the past, high-level performance is not new. Find a mentor who has coached for at least forty years, learn from their success and mistakes. Learn from other sports, broaden your horizons. Look at dance and music for creative ideas on rhythm and movement. Keep challenging yourself to get better. Set the example for your athletes. Learn to listen better. Learn to see more. See your sport with childlike eyes.
Coaching is a way of life, you must live it to be good at it, there is no app for that.