For being a police officer in state police or central cadre (like IPS) you need to be a graduate at list for Inspector/SI level as well as IPS. Now for some other posts in police it may demand 10+2 pass in any stream. Also nowadays the cyber cells in police are taking a lot of officers which will need you to have science in 10+2 as well as graduation.

Now depending on your interest you have to choose the course. If you go for any course in 10+2 and in any graduation course then you will be eligible for 99% of the police jobs.

To get the notifications you need to keep an eye on your State PSC website as well as Central websites for Central Cadre services.

I hope this helps.