im looking for a winter footwear,and i liked RONDANE GTX RR BOA WL the problem is i dunno whick size i should choosez my feet size is 27.5 in socks , this footwear model wide and i dont know which amount of wxtra space should i add ? im planning to use those boots during hiking

what does that means true to size ? and ive heard as someone said about that 1 cm is too little and 2 cm is enough(is that true ?) for a very long hike since foot will swelling after a long hike