WCIF arms outstretched

It is possible to change arm positioning (which includes arms-down poses in live mode, I believe) on a per clothing item basis by editing the item, and it is possible to change the position of all Sims' arms in CAS all the time, but I'm not aware of any way that you can change the position of a Sim's arms in CAS based on what clothing item they are wearing without editing each clothing item. (To change all Sims' arm positions all the time, you can use a stand still in CAS mod that puts Sims in a t-pose.)