Going by last few years' question analysis, we have the chapter wise weightage.

Physical-world and measurement 2%
kinematics 3%
Laws of Motion 3%
Work, Energy and Power 4%
Motion of System of Particles and Rigid Body 5%
Gravitation 2%
Properties of Bulk Matter 3%
Thermodynamics 9%
Behaviour of Perfect Gas and Kinetic Theory 3%
Oscillation & Waves 3%
Electrostatics 9%
Current Electricity 8%
Magnetic Effect of Current & Magnetism 5%
Electromagnetic Induction & Alternating Current 8%
Electromagnetic Waves 5%
Dual Nature of Matter and Radiation 6%
Optics 10%
Atoms & Nuclei 3%
Electronic Devices 9%

So most of the questions come from the chapters with higher weightage. Like electronics devices, Thermodynamics, Optics, Electrostatics etc are important chapters and every year questions come from these parts.
However, there are chances that Neet 2021 syllabus will be reduced as the academic year has been delayed and due to this pandemic all educational institutes are closed so it is difficult to complete the entire syllabus. To complement that, CBSE has reduced the syllabus 30%.
However, Careers360 has come up with Neet knock out package to help medical aspirants in their preparation. http://learn.careers360.com/knockout-neet-may/