Is there a way to determine strain

A customer has a question and I hope we can get some opinions on it, thanks

I’m a first timer having unusual success. I’m growing bag seeds I have 3 questions: is there a way to determine strain (seeds came with medicine ordered from B.C) how big a pot should I transplant to if I don’t know how big they’ll get and should I be “pinching” back if I have plenty of room to grow in? I have other questions, but pinching and transplant are the stage I’m at. Look forward to hearing from you.