Hey,
The eligibility criteria to become a bank clerk includes minimum a graduation degree from any  government recognised University.
The other requirements include the candidate to be proficient in the official language of the state. Moreover,a candidate should be able to operate the computer and basic operation on it. The minimum age must be minimum 20 years and the maximum 28 years of age. There is five years age relaxation for SC/ST and 3 years age for OBC.
Hope this helps you.
Good luck.

Hello aspirant,
I am sorry to tell you that you cannot join bank after 12th.
You cannot join bank till you become a graduate from a recognised college or university.
You cannot even join bank as a clerk.
The sum of all the substance is you cannot join bank after 12th that is before graduation for the higher post.
I hope this answer was helpful.
All the best.

Hello aspirant,
I am here for helping you.
Your doubt was about joining bank jobs after class 12th so, sorry to say but you can not join any of the bank job after your 10+2. minimum eligibility criteria which you will have to fulfill for giving any of the bank job exam is to complete your graduation.
For knowing more about bank job exam and eligibility criteria you can go on the link which I am providing you below:
https://competition-careers360-com.cdn.ampproject.org/v/s/competition.careers360.com/articles/bank-jobs/amp?amp_js_v=a2&amp_gsa=1&usqp=mq331AQA#referrer=https%3A%2F%2Fwww.google.com&amp_tf=From%20%251%24s&ampshare=https%3A%2F%2Fcompetition.careers360.com%2Farticles%2Fbank-jobs
I hope it will help you.
For more queries you can upvote me and can ask in the comment box.
Best of luck.