Can I scored above 240 in ( mains and advance ) 2019 without any coaching?

You can definitely score above 240 with right strategy and focussing on your weak areas.

Coaching institutes help you in clearing doubts and guiding you the right direction, however, you can score well without coaching as well.

All you need is full dedication, peristent efforts in focussing weak areas, sharpening your strong areas and analysing mock exams to identify how much time you devote to wrong qanswers and if there is any substitute method to solve.

For your reference, some useful prep tips have been shared below:-

https://engineering.careers360.com/articles/jee-advanced-preparation-tips-physics-chemistry-and-mathematics

To know the paper pattern and devise right strategy kindly refer brelow link to know the differene between JEE Mains and Advanced.

https://engineering.careers360.com/articles/how-jee-advanced-different-from-jee-main

Scoring good marks in your exam totally depends on you. Coaching center can only provide you direction. There are many students who have cracked JEE exam without coaching classes. If we look statistics then there are about 52% students who have cracked JEE exam by doing self study. It is one of the competitive exam you need to really work hard to achieve your aim. You have enough time to prepare. So, you can plan your preparation accordingly. Make your proper time- table and make sure you follow it. To score good marks in JEE exam make sure your basics are clear. Build your concepts strong. So, that you can easily do tricky questions. Before starting your preparation you should be aware of the complete syllabus. Important topics and exam pattern. Refer previous year papers to understand the exam pattern and level of questions. Once you complete one topic solve MCQs related to them. Give importance to NCERT books as syllabus is based on them. Practice as much as you can. Solve complete mock test series to check your performance level at regular interval of time. All the Best for your Preparation!!