Hello there!

Hope you are doing fine.

To become an airline pilot, you can choose any one of the following two paths after completing class 12th with PCM.

First, go to a flying school, get your license after proper training and work as a pilot.

Second,

Get a Bachelor's degree in any of these: Aviation, Aeronautical Science, Aeronautical engineering, Aerospace engineering, Avionics engineering from  any good colleges/university.

After completing Bachelor's, you can go for master degree or direct work on entry level.

For more information, you can click on the given link:

https://www.careers360.com/careers/airline-pilot

Hope it helps.

Stay safe.

Best wishes.