If you want to study the course of Computer Science Engineering, then you need to compulsorily have PCM in your 10+2 course. The subject of computer science isn't compulsorily. So even if you don't have CS in your 10+2 but you are a PCM student, then also you are eligible for the course of BTech Computer Science Engineering.

For more information regarding BTech CSE consider the link below:

https://www.careers360.com/courses/b-tech-in-computer-science-and-engineering

I hope this helps. Wish you a great eve!