You need to do the mentioned below things in order to study Bachelor of law course after completing 12th class:

1. First of all you are required to complete our degree in graduation level. You must have completed your graduation degree from a recognised University.
2. You need to score at least 45% to 55% marks in the aggregate of graduation examinations for being eligible for admission in different colleges and Universities for LLB course.
3. Some colleges and Universities also conducts entrance examinations for providing admission in LLB course.

Read more:

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.careers360.com/courses/llb-bachelor-of-legislative-law/amp&ved=2ahUKEwjGovHgt6n2AhXiyzgGHZXmBlUQFnoECA0QAQ&usg=AOvVaw0b6DacVZKawZAB6StucJtI

Hello
Hope you are doing well
To get into llb/law you will have to write entrace exams, some of them are :
List of exams can be taken to pursue Law education in India
CLAT - Common Law Admission Test.
AILET - All India Law Entrance Test.
LSAT - Law School Admission Test.
LSAT-India - Law School Admission Test (LSAT-India)
SLAT - Symbiosis Law Admission Test.
BHU BLAT - BHU BA LLB Admission Test.
MH-CET - Maharashtra Common Entrance Test - Law

However,There are many law colleges in India who give admission based on 12th marks. So do apply for those colleges and merit list is solely decided upon the 12th marks. No need to appear for an entrance.