I also have a 2018 Leaf and when I fully charge, the "guessometer" is all over the place. In warm weather I have found it to read 160 miles, some have even posted higher results. When it is cold out, the number is lower. The lowest it has ever shown is 130 miles on the full charge. It has been told to me there is a computer that is tracking your driving habits, and other things to come up with this number. When the heat or AC is on, this number is lower. I am not aware of anything you can do to tweak this figure.
PS. Welcome to the forum.
2018 Gun Metallic Gray, SL, Technology Package, etc.