Hello Vinay!

If you want to become a class 1 Police officer, you need to clear the IPS (Indian Police Services) exam conducted by UPSC.
For you to give IPS exam, Condition is that you must be a graduate and in the age limit of 21 to 32 years.
So you cannot apply directly after your 12th boards.

For more details on eligibility criteria, visit:
https://www.google.com/amp/s/competition.careers360.com/articles/upsc-civil-services-eligibility-criteria/amp

Hope this helps!
Thank you :)