are some pcs already decided?

Read carefully. The person specifically is asking about fraternities, not sororities. Your response is not answering their question.

That said, it is true that sororities do not decide pledge classes before recruitment.

In response to the OP, Clemson fraternities SEEM more laid back and more open to OOS students compared to fraternities at schools like UGA, but it's not clear if some of the ones who attract more in-state students have a good proportion of the pledge class decided already. What I have seen suggested on some of the other schools' pages is to let the rush chair for each fraternity know you are interested in rushing as soon as possible so at least they know who you are before rush. There are a lot of OOS students in fraternities here, though, so you should be able to find your place, especially in those fraternities that have more OOS members. There are good ones.

Beta phi delt delta chi alpha sig and pretty much most lower tiers are all pretty easy for out of state people to join