To know the official syllabus of CBSE 11 and 12 for the academic year 2021-22 you may visit the link provided below:

http://cbseacademic.nic.in/curriculum_2022.html

For the preparation strategy of class 12 visit the link provided below:

(http://cbseacademic.nic.in/curriculum_2022.html) https://school.careers360.com/articles/cbse-class-12-preparation-tips

I hope my answer helps. All the very best for your future endeavors!