Depends what sounds you are talking about. If it’s footstep or something then attaching to the character and applying dependent on physical material is the way to go. For actual ambient sounds you could spawn them on the character based on some circumstances but placing them around in the level is sufficient for most. If you are going for binaural audio then this kind of placement is actually quite important because you want to hear the sounds from a correct distance and location and have other objects interfere with them. But if you just want to hear some wind then sure attaching to the character works fine.