what are some scoring and short chps or topics for jee so that if we study them well we could aim a high score of 210+?

Hello aspirant,
There are many topics in maths, chemistry and physics Which carry a huge weightage in Jee and by preparing those well, you can ace a score of 200+ easily in Jee mains,however if you are aiming for such a high score you should revise and learn each and every topic for Jee instead of going through short cuts
Some important topics are:
1. Calculus, coordinate geometry(very important) , probability, differential equations ,limits, definite integralsfor maths
2. Electrostatics, magentostatics, rigid body dynamics, optics, thermodynamics, error and measurement(for mains) for phyics
3. Solution and colligative properties,  organic chemistry, p block, thermodynamics,electrochemistry for chemistry.
Hope it helps.