I have a prehung exterior door that is a LH inswing (brand new not installed yet). Can I somehow switch it to make it a RH inswing? Would it work if I installed it as an outswing?
It is impractical, if not impossible to make a pre-hung/pre-drilled door (for knobs and locksets) change swings. The exterior is different than the interior in most models and the hinge mortises are on the wrong edge of the door. If you install it backwards, or swing to the outdoors, you may have a problem with the threshold. Many thresholds slope to the outside to shed water. If you reverse it, then water could flow indoors. Another consideration is that you cannot install a storm door if the door swings out.
Outswing would make it a Right Hand Reverse door (RHR). Changing the hand to make it RH would require you changing these preps ( door hinges , frame hinge , Door hardware preps , frame hardware preps ) . However this may not be practical on certain HMD door scenarios. That being said I recommend you exchange the door for the correct hand . If you are asking this question chances are good you are not equipped to pull this off