Hey there

The state PCS is an exam which you have to clear once and you get the post and thus a lots of hard-work is needed to clear it as it's a government job and many students apply for it. CA is an exam where you have to give various exams in the entire course each exam is very tough in terms of paper toughness and competition too. But seeing the competition state PCS is tougher to crack. 21 is a good age to start the preparation for any of them. English is not a barrier in any of two exams just a decent English is enough to crack the exams.

Good luck