Hey.
As you are seeking to do law after graduation
a 3 year LLb degree is suitable for you. You can apply for admission to a 3 year LLb course while you are in your final year.
Your admission will be based on your score in the entrance tests. There is no common entrance, each college has its own entrance. Few of the entrances for a 3 year law course are-
DU LLb- Delhi University
MH CET- GLC Mumbai, ILS Pune and other law colleges in Maharashtra  PU LLB- Panjab University,Chandigarg
TS LAWCET- Law colleges in Tamil Nadu
BHU LLB- Banaras Hindu University.
BVP LLB- Bharatiya Vidyapeeth University
LSAT- Private Law colleges like O.P. Jindal Global Law school, IIT Kharagpur etc

You can use the link below for any other information.

Https://law.careers360.com/articles/9564-law-entrance-tests/amp

Best of luck